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The Case of the Lost Transmission: Newsletter Challenge (October 2012)

Posted September 30, 2012 12:00 AM

This month's Challenge Question: Specs & Techs from GlobalSpec:

Cars powered by internal combustion engines need transmissions. However, electric cars and steam locomotives do not need transmissions. Why?

And the answer is:

The problem with the internal combustion engine is that it produces a very small torque at low speed (approximately below 300-350 revolutions per minute). When you start the engine and if you have a load engaged with it, even if the load is very small, it will stall the engine. This is the reason a clutch is needed to disengage the engine from the transmission gears (the actual load) at low speed and to gradually engage the load when the rpm reaches a high value (normally over 1000 - 1200 rpm). Steam engines and electric engines develop full torque as soon as the engine is started.

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#1

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 1:10 AM

Because full torque is available at zero or low rpm; also, steam engines and electric motors can start from a dead stall without clutches.

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#2

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 5:53 AM

Low end torque....

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#3

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 8:05 AM

Yes, low end torque for the electric motors. In a steam engine the steam tank can build up a large 'head' of steam before the valve is opened to the piston chamber (or turbine chamber).

An IC engine needs to be already turning before fuel is injected into the combustion chamber.

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#4

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 6:46 PM

It's all about torque. Torque is what actually accelerates a car, not horsepower (torque = force X distance). Enzo Ferrari once said, "Horsepower sells cars, torque wins races"

Compare the torque curve from the Tesla EV to those of a high performance combustion engine and a commuter car.

With virtually 100% torque available at 0 RPM there is no need to have successive gears, although some EVs use them to extend the high end speed when they have a more limited RPM range than some internal combustion engines.

On the flip side, we just returned from the Florida coast to coast road rally and there is nothing like the scream of a GT3 at 8,200 RPM.

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#5

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 10:46 PM

Actually... it doesn't. It just would not be as efficient nor smooth, but an internal combustion engine could do away with a transmission.

Technically speaking, a flywheel with a "clutch" could be used to engage / disengage drive which would also be true for an electric or steam engine. Over coming static energy or initiating motion would be the biggest challenge but the same would be true for steam or electric motors. Any or all would have that "wind up" effect where in speed would have to be built up if the transmission was done away with, although with electric motors, other possibilities / options are available.

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#6

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 11:00 PM

internal combustion engines operate over a small range of RPM with high efficiency. At idle = just enough to keep it turning over, and they have zero power at zero RPM. Gas engines have a wider range of power output than diesels, as 1200 rpm to 5000 rpm with max efficiency being a broad peak at around 3000 rpm and max horsepower at 5000 rpm, more or less. Diesels have a much narrower power range, say from 1800 to 2800 rpm, with a limited max of ~3500 in truck engines. VW jettas have been made smaller and wider range to avoid excess gearing.

Large diesels run even slower.

So a truck might need 8-10 gear changes to change the vehicle speed from stopped to 60 miles per hour - all this to keep the engine in the correct torque and speed range. The reason for doing this is the greater efficiency of diesel engines in terms of oil used per ton mile. A typical truck carries 40,000 pounds = 20 tons, and might get 3 miles per gallon, maybe more lately. at $4/gallon = $12 per mile = 60 cents per ton-mile. The truck goes 60 miles per hour and the driver is paid $20 per hour or 33 cents per tone-mile

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#10
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 6:47 AM

Your assumptions are somewhat out of date. But, your math is way off. Better check both.

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#11
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 7:18 AM

yes inverted math oops

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#7

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

09/30/2012 11:53 PM

Steam engines (piston type) can develop AND MAINTAIN pressure on a piston regardless of whether that piston is or is not moving. Assuming that there are a minimum of 2 pistons (1 stroke system) so that there is always a pressurized cylinder that is not at TDC or BDC, it is always capable of providing torque without motion- or starting away from a stalled position by increasing the steam pressure to the required level. Likewise, an electric motor can generate a significant level of locked rotor torque- although at a huge current draw- and is also capable of starting from a stalled position. In both these cases this eliminate the need for a clutch or torque converter, although they may still provide beneficial for certain applications.

They also have a fairly consistent torque output throughout their available rpm range that allows a correctly geared system to operate from standstill to "redline" without the need to vary this ratio, as the power source is always outputting close to full torque, and so develops full horsepower at close to maximum speed where it would be needed. They can be combined with a transmission if desired though.

Typical internal combustion (IC) engines are kinetic machines- due to the nature of the cycle they require a certain amount of momentum to keep working. This minimum is practically reflected by the idle speed- much lower and they will stall (even diesels, though you can turn them down pretty far!!). This means they need a clutch or torque converter at a MINIMUM- and don't HAVE TO have any more, look at go carts- to allow the vehicle to slow below the speed the vehicle will travel at when idling, come to a complete stop without causing the engine to stop, disconnect the engine from the drivetrain to allow it to be restarted to resume operation without the hazard of forcing the vehicle to move while doing so, and to allow slippage in the drive system as the vehicle speed accelerates back up to match the engine rpm's.

Due to the fact that IC engines do NOT produce a torque output as linear as the stem piston or electric motors but tend to be most efficient in a somewhat narrow area of the power band, they are typically coupled with transmissions that allow the selection of different gear ratios. This allows the engine to operate close to this "sweet spot" of power and efficiency over a much wider range of vehicle speeds than allowed for by a single fixed ratio (with the very low engine speeds & large number of transmission gear ratios available on a large semi truck, this could be a variance of less than 500 rpm engine speed from a standstill to highway speeds). One other thing that is often forgotten is that this allows a vehicle to be capable of driving comfortably at highway speeds but also operate at much lower speeds than that gearing alone would allow without having to slip the clutch or rely on speed reduction/ torque multiplication within a torque convertor because it is dropping below the engine stall speed.

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#8

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 3:02 AM

Maybe I'm just not seeing it, but there's an additional factor besides the "torque-available-at-zero-rpm" issue that no one has mentioned. At least in theory, a sufficiently "loose" fluid coupling would make it possible, if not practical, to do away with the transmission; one can imagine a non-Newtonian fluid being used in order to make it workable.

The other factor: both conventional steam engines and electric motors can be run in the reverse direction. MOST internal combustion engines cannot. Still, at least one type of motor vehicle has been made that used an internal combustion engine which could be deliberately started and run backwards to provide a reverse gear . . . The motor was a two-stroke (no valves) and the electric starter was designed and purpose-built to provide bidirectional capability.

Who recognizes what type of vehicle did this?

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#13
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 9:29 AM

"At least in theory, a sufficiently "loose" fluid coupling would make it possible, if not practical, to do away with the transmission"

could you call it "Powerglyde"?

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#14
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 10:04 AM

"could you call it "Powerglyde"?

Oooh - what a perfect name, so reminiscent of a loosely-coupled system of yore . . . !! We used to refer to "slush-o-matic" when I was a teenager, to cover most of the systems in use back then.

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#9

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 5:44 AM

Steam engines do have gears, though.

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#12

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 8:29 AM

It used to be true, very recent designs have a 2 speed gearbox to improve life of components and to quieten down screaming motors......

So basically, its not completely true anymore......and will get even less true as designs improve.

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#15
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/01/2012 11:12 AM

I have a engine that can run forward or backward ..Most of us have seen these engines working years ago ??? Where, on the railway .The speeders all had them .They would slow the engine down and when it was just about stopped they would move a leaver causing the moter to run in the opposite direction

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#54
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/19/2012 11:54 PM

Marine diesel engines. were often direct drive reversible engines. I operated one in a large tug boat when I was much younger.

The lever changed the valve train order, to go from forward to reverse with the engine at stop. then restarted in the opposite direction. I believe it was a Fairbanks Morse engine of about 500 HP.

Some Oliver Tractor engines in tractors would change direction by simply starting it in the direction desired. Not too handy when you stalled on a hill and rolled back, they would start in the reverse direction and if the throttle lever would be set at a high rate of speed. Very scary.

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#55
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/20/2012 6:03 AM

How true, but at least you had power for a rapid "U-turn" to get you facing in the right direction!!

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#16

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 12:45 AM

The local military base used to have on their own "railroad" a direct drive locomotive with a reversable diesel engine.

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#17

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 3:07 AM

Still don't see anyone knowing about a reversible gasoline engine vehicle. I'm thinking of the Harley Davidson / Columbia Par Car golf carts! They had a lever down low that set the direction that the starter ran. To reverse, you had to stop the engine, move the lever, re-start, and then go backward. Same procedure to go forward once again.

Here are pictures of their starter/generator. Note that there are at least five (5) terminals on it! http://www.fleetalternatorstarter.com/starter_generator_60106.aspx

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#18
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 3:14 AM

How did they reverse the timing?

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#19
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 3:51 AM

Hmm - that's a very good question! I didn't look that closely at the engine when a buddy of mine had two of these odd beasts. I can think of several possibilities, though.

If I were designing a two-stroke to run backward only a small portion of its life, and preferably only at a low speed, I might consider letting the timing stay where it is, giving a VERY retarded ignition, far after top dead center (ATDC), when in reverse. But a little deliberate slack in any of several locations could serve the purpose. For example, a bit of clearance on a drive lug for the cam for ignition points would do the trick; it might even have, say 340 degrees of backlash, and run at 10 degrees BTDC in either direction. Hypothetically, another trick would be to have twin ignitions; whichever one fired first would ignite the fuel, and the second would be a wasted spark. "Wasted spark" ignition systems do exist, and Harley has used them: see http://en.wikipedia.org/wiki/Wasted_spark. However, this is a noticeably different method that I'm describing.

I'll try to catch up with him and ask if he checked out how it was done on the ones he had (didn't have them very long; re-sold them both). I saw the underpinnings, but didn't run them or study a lot of details.

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#20
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 4:08 AM

I suppose another way would be to have ignition right at TDC, taking a modest hit on efficiency either way.

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#27
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/04/2012 11:39 AM

True - but why take the hit BOTH directions? Reverse might be, what, 1-2% of the distance that the vehicle travels forward, for cars, trucks, and golf carts)? Corvair used a buttress-tooth ring-&-pinion to give additional durability in forward gears, sacrificing gear life in reverse, so it's not a new concept. Many of the non-intersecting-axis designs have a similar issue, with asymmetric gear tooth profiles. Sure, lifespan in reverse is short, and additional loads are thrown onto the bearings when in reverse, but it's for such a tiny percentage of the overall use, who cares? For ignition, same deal: take a bigger hit in reverse, and optimize forward.

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#57
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/20/2012 11:56 PM

shifting the gear in timing gear box that changed the direction of rotation of the cam shaft. It was done on the front end of the engine housing with a lever.

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#58
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/21/2012 3:37 AM

"shifting the gear in timing gear box that changed the direction of rotation of the cam shaft."

Ummm: no. These were two-cycle engines, and had no normal valves, and no cam(s), and thus no gears to drive said non-existent cams. I quote directly from the "1963 to 1980 Gasoline Car Service Manual: the maintenance and repair information in this manual applies to the 1963 to 1980 Harley-Davidson(r) Gasoline Golf Car, Models D, DF, DC and D4." (I have a physical copy in front of me, obtained directly from the owner who I mentioned previously; revision 7/79.) Page 1-1:

"ENGINE....... D

Type of Engine...... 2 Cycle - Loop Scavenged 1 Cylinder Reed Valve Intake"

From page 3-1:

"Engine Description. The Gasoline car engine is single cylinder, 2-cycle, air cooled. Oil is mixed with gasoline for fuel and lubrication. The engine has two major component assemblies - cylinder and crankcase.

The cast iron cylinder assembly includes an aluminum head and aluminum piston. The cylinder and head are bolted to the engine crankcase. The gasoline charge is admitted to the cylinder and exhaust gas is ejected from the cylinder through ports in the cylinder wall.

During the upstroke of the piston, a suction is created in the crankcase and the reed valve opens drawing a gasoline and air mixture from the carburetor into the crankcase. at the same time, compression of the previous charge takes place above the piston.

After ignition, on the downward power stroke of the piston, the exhaust gas is ejected from the cylinder. At the same time, gases in the crankcase are compressed and forced up through the cylinder transfer ports, into the combustion chamber as the descending piston uncovers these ports."

And, most closely covering the question that Tornado asked (#18), on page 5-2 [1967 and Later D Model]: "Ignition spark is produced by a 12-volt coil through a cam operated circuit breaker designed to give correct ignition timing in both forward and reverse engine running directions." Granted, there is no mention of what sort of mechanism does that changing of the timing, but the manual specifically says that there was such a system in place.

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#60
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/23/2012 11:28 PM

not the theme of the challenge, but:

you have to fuel the cylinder before you can ignit!

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#22
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 4:29 PM

For reversible gasoline engines....

Look at 2-stroke snowmobiles!

Polaris' system is called "PERC"

I am not sure what Ski-Doo's is called.

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#21

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 6:15 AM

Stanley and White Steamers had 2 double acting pistons. So were equivalent to having 4 cylinders with single acting pistons. This allowed them to be self starting as they had a power stroke starting every 90 degrees. Though I wouldn't say they didn't need a transmission. The piston steam engine uses variable cutoff which is some what equivalent to a transmission. From a stop and very slow operation they used a long cutoff admitting steam for more then 50% of the stroke. As speed increased the cutoff was reduced so as to use steam more efficiently. With out that cutoff reduction their steam pressure would have been drawn down at speed as the boilers did not have the capacity to maintain steam production at such high rates. So in a way the cutoff control replaced the transmission. Stanley's were all direct drive. The start up procedure required the operator to jack up a rear wheel so the engine could be run initially to get any water out of the cylinders as the engine wormed up. So a disengagement mechanism could have been used. The White steamers had a two speed gear box with a neutral position so the start up procedure used the neutral position.

A modern efficient steam automobile could use a multi speed gear box. Efficiency of a steam engine is dependent on the expansion ratio. It is during expansion that heat energy is being converted to work in the engine. During admission the engine is operating on heat energy converted into work in the boiler. Operating an engine non-expanding is the least efficient. There is always a down side though. Expanding steam to below the external cylinder pressure results in an efficiency loss. When the exhaust opens steam is drawn back into the engine and must be pumped out by the piston up stroke. So the engine in over expansion is wasting energy. An automobile needs a power range to control speed. Aerodynamics makes that a cubed relation of power. A square relation to torque. The power being controlled by throttling steam is limited by the engine going into over expansion. That is throttling the steam is basically reducing admission pressure. Expansion being constant, throttling than lowers the end of expansion pressure. The higher the expansion ratio the shorter the efficient power range. The most efficient way to operate a piston steam engine is with no throttling an expansion to the external cylinder pressure. However with a normal engine that would operation mode would have mo power control. A steam engines power can be controlled by cutoff. As cutoff limits the volume of steam admitted. But varing cutoff varies expansion ratio in a normal engine. A new method of controling expansion ratio by varing cutoff and clearance (the volume when piston is at TDC), that was first developed by the Williams Brothers in a uniflow engine to prevent over compression, shows another way of varing power by physicly controlling the clearance and cutoff together to maintain a constant expansion ratio. Such an engine could be designed to operate efficiently over a large power range and would need no transmission or disengagement device as the valves could be simply be held open during worm up of the engine.

Here are some links to interesting steam car vid:

http://www.youtube.com/watch?v=uJ2K6TCv2kw Chucks Steam dregster

http://www.youtube.com/watch?v=I4rDjTN2JMs A ride in a 1906 Stanley

http://www.youtube.com/watch?v=JZ2oI6pixQI&feature=relmfu 1906 Stanley in a hill clamb event.

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#23

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/02/2012 5:58 PM

The early Cadillacs, Oldsmobiles, and Pontiacs had a four-speed automatic with a fluid coulpling (Hydramatic) that felt as solid as a manual tranmission. The Buicks, however had the Dynaflow which gave an infinite range from zero miles per hour to top speed. They were great for burrowing your way out of a snowbank. They did have a low and reverse gear though. When Star Trek became popular we called those Warp-Drive transmissions.

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#24

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/03/2012 1:50 AM

usually combustion engines have an idle speed of more than 10% of the highest revolutions of the engine; this results in a lowest speed the motor can drive a car. By this reason a combustion engine driven car needs a clutch and a gear.

electric cars use an electric motor, this revolution controlled motor gives the greatest torque at the lowest revolution (P=M*n, where n ist the number of revolutions per time unit), if the electric car stays - the motor gives (theoretical) his greatest torque to the wheels (as long as there is no other resistor like power control, track control in formula 1 cars).

A steam locomotive needs no idle speed - so the steam can do his work every time (as long as it is steam).

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#25

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/03/2012 6:12 PM

Actually, in today's state-of-the-art, electric cars DO need transmissions. Although it is true that electric motors produce enough torque to motivate heavy vehicles even from a full stop, they draw gobs of current to do so. Today's batteries cannot tolerate that abuse for long - you will kill your range and shorten their life. Since battery power is so precious today, you need to conserve it by taking advantage of the mechanical advantage that a transmission provides. You do not need as many gears as an internal combustion engine does, but a low gear for launching and a higher gear for running will extend battery range and life quite a bit. This I've learned by building and experimenting with several electric car conversions.

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#26
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/04/2012 4:32 AM

I mentioned that in post #12, nobody gave it a GA.......why is it worth a GA to show that we both are up to speed (pun intended) on electric vehicle gearboxes and the need for them?

Have a great day.

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#43
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Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/13/2012 11:24 AM

Don't know Andy... don't matter to me. Maybe because I was more wordy?

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#28

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/05/2012 6:57 AM

IC engine speed can't be controlled over a wide range. Hence there is the need for reducing the speed by adopting a gear box. The basic purpose of the transmission is to match the speed of the wheel shaft as per the desired speed of the car irrespective of the engine shaft speed,

In case of electric car or the steam locomotive, the electrically or the steam driven engine speed can be smoothly controlled to match with the speed of the wheel shaft without the need of any intermediate transmission gear.

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#29
In reply to #28

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/05/2012 7:56 AM

NOt exactly true. MOst EV motors actually have a smaller RPM range than many cars. For instance, my car has a redline above 8,000 RPM, but no torque below 1,500 RPM.

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#30

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/09/2012 1:16 PM

A misleading question based on a false premise.

Said movers DO have transmissions, what, how will power be transmited to the ground without a transmission?

The false assumption that every post I scanned makes is that "transmission" means "gear reduction ratios"

That is a false assumption.

A transmission is a system to transmit power, it is not solely defined as torque/speed division or multiplication.

An AXLE is a transmission member.

And yes, someone correctly stated that engines do not make horsepower.

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#31
In reply to #30

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/09/2012 2:28 PM

The false assumption that every post I scanned makes is that "transmission" means "gear reduction ratios"

At least in the automotive sense (implied by the framing of the challenge) "transmission" and "gearbox" are fairly much interchangeable terms. Nor are all ratios reductions, either; the very word "overdrive" is the technical way to say that there is an INCREASE in output RPM relative to input RPM. Granted, when coupled to internal combustion engines, there is ordinarily an RPM reduction in the final drive / differential stage.

An axle, a transmission, a drive shaft, CV joint / universal joint, differential, etc. are some of the possible parts of a "power train" or "drive train", in that same automotive sense. Yes, it is legitimate to say that they transmit power, but they are NOT "transmissions", at least in automotive terminology.

The layout of late (early 1930s) Doble steamers would have made it possible to bolt the wheels directly to both ends of the crankshaft, BTW. Thus, no axle, per se. In-wheel motors for electrics also dispense with any such item. At least some designs have been made such that the wheel [rim] itself is the rotor of such a motor. Would you then say that the tire is now a transmission? Then envision something like the moon buggy, where the rim could become the ONLY moving part, and figure out what to call a transmission...

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#34
In reply to #31

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 4:32 AM

I think that the use of the word transmission for the gearbox is a mistake made by many people. Lay and non lay people make this incorrect over simplification.

When someone says today "the transmission is broken", he usually means the gearbox, but technically its not really clear. He is basically saying that power from the engine is not reaching the driven wheels.....

The word transmission should only be used for the complete drive chain from motor to wheels in a fully correct terminology.

In this drive chain you could have the following individual parts (at least!):-

Clutch

Gearbox [with or without any change(s) of RPM]

Drive shaft(s)

Differential(s)

Drive shaft(s) Again

Wheels

Then there are so called "transaxles", which are a possible combination of most if not all of the above in a single unit......

I looked up the word in the online Oxford dictionary, which appears to understand the same concept:-

Definition of transmission noun

  • 1 [mass noun] the action or process of transmitting something or the state of being transmitted: the transmission of the HIV virus
  • [count noun] a program or signal that is broadcast or sent out: television transmissions
  • the mechanism by which power is transmitted from an engine to the axle in a motor vehicle.

I hope this helps further.

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#35
In reply to #34

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 6:00 AM

"The word transmission should only be used for the complete drive chain from motor to wheels in a fully correct terminology."

But then the original question becomes meaningless, given that both electric cars and steam locomotives have wheels, and often, other components from your list.

That is, in part, why I specified "in the automotive sense" of the word. Try looking up the terms "automatic transmission" and "manual transmission" (I don't have access to the OED on-line, but other sources often show "manual gearbox" and "manual transmission" as interchangeable terms). This should narrow the context to a range suitable for this Newsletter Challenge, rather than how it might be used in biology or electronics. Nearly all of a drive train could be identical between cars of the same make, model, and year (except for use of a fluid coupling, usually, instead of a clutch) when purchased with either automatic or "stick shift " [manual transmission]. It is that single assembly - the gearbox - which defines whether the car is considered "automatic" or "stick".

"Transaxle" is used to describe an assembly containing both the transmission and differential; these come in both automatics and manually-shifted versions, with the car's type still defined entirely by the transmission portion.

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#36
In reply to #35

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 7:59 AM

I think the original question was simply, "why do electric cars not have multiple gears to cover the full operational speed of the vehicle."

The answer they wanted is all bout electric motor torque vs internal combustion engine torque.

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#37
In reply to #36

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 11:00 AM

I think the original question was simply, "why do electric cars not have multiple gears to cover the full operational speed of the vehicle."

Exactly right! Thus, by using the word "transmissions", the Newsletter Challenge means [IMO] "that device interposed between the engine and drive axles which has multiple gears." It could be a two-speed box, a 3-speed, . . . up to a continuously variable one, but it is not ALL of the other components of the drive train. None of those other pieces changes ratios during operation of the vehicle, though a two-speed rear end might fall into a gray area. Those fell out of favor by about 1940, though; I have never even seen one.

Those components do transmit power from the engine to the wheels, but are not, themselves, "the transmission." That term is reserved for the multi-speed (and reverse!) gearbox, as used here.

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#56
In reply to #37

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/20/2012 11:50 PM

Many current light duty dump trucks or delivery trucks use two speed axles. Larger Trucks use 8/10/12 speed transmissions, with an electric range changer. Your premise is correct though, transmissions/gear boxes are not the only axle speed changer possible.

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#38
In reply to #35

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 12:11 PM

You describe the mistake many (including myself) have made over many years, but it is still wrong.

Even dictionary's show that its wrong and its to them we must turn to, not just opinions from people with only a tenuous grasp of English.

We won't change such people over night, if at all, but we should try and strive to make such things far less ambiguous than they are at this moment....

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#40
In reply to #34

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 1:36 PM

what about the transmission line?

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#41
In reply to #40

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 1:56 PM

Do you not understand what I wrote?

Or is it your idea of humor?

Let me know if you need any further help in this matter.....

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#50
In reply to #41

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/17/2012 1:30 AM

you are talking about yourself!

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#52
In reply to #50

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/17/2012 3:35 AM

100% Wrong again! How sad for you!

Do have a great day anyway......

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#32

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/09/2012 3:01 PM

Externally powered motors are, in a sence, transmissions. Electricity or steam are stored outside of the engine or motor, then transmitted to the motor, and are then transformed into kinetic energy by the motor, thus making the motor a transmission of sorts.

The internal combustion engine is it's own energy generator. However, it makes kinetic energy that must be clutched in some way to shield the drive train (and your teeth) from excessive stess while transferring energy to the ground.

ln other words; steam and electicity are like "soft" energy that acts like it's own clutch.

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#33

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/09/2012 4:22 PM

IC engines, inherently have optimum power at a certain RPM. Transmissions generally provide for the engine operating at or near that range. An electric motor and steam engine are supplied by a separate "power source"; i.e., electricity or steam, and as such their power output is a direct result of the power input. This, at least inp art is why electric motors are considered more effiicent than IC engines.

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#39
In reply to #33

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 12:39 PM

Of course any vehicle that contains internal energy for the purpose of moving from place to place must have a means to transmit that energy to whatever drives it. It may be as simple as a copper wire or as complex as an eighteen wheeler.

The day is coming when elaborate gear sets will become as obsolete as hand cranks on automobiles. Ten years ago I came up with a design that used a battery and an Algae derived bio-fuel to run a Gen-set. At that time, I thought that oil derived from Algae was the best source of alternative energy. Now I'm not so sure.

An exciting approach is providing external energy to the automotive drive. Certainly this is not new. Just look at San Francisco's Cable Car system. Atlanta once had the most amazing Electric powered bus system, driven by two overhead wires. Aesthetics did away with them, much to the chagrin of thousands of daily passengers.

A recent proposal is, to bury electric wires in all of our roadways and use this infrastructure to provide induction power to all road transport. A relatively small battery would get you from home to the nearest buried power source. All of this system could be made seamlessly by proper design and engineering.

I have owned Hybrid automobiles with Continuously Variable Transmissions (CVT) for about ten years. It didn't take me long to realize that I would never go back to clunky, jerky Automatic transmissions. The day will come when pushing on an accelerator will transmit a variable signal to an escapement that will tell all four wheels what direction to turn and how much torque to apply .

It's not written in stone that you can only use one, two or four electric motors. How about sixteen small ones? Properly controlled they would enable a very smooth and efficient acceleration. They may even have external rotor, highly efficient electric motors. The transmitting of the drivers wishes could be a simple wire or it could even be wireless. After all, the keyboard I am typing on is wireless. It hasn't missed a stroke in over a year.

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#42

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/10/2012 5:13 PM

In high school I got an old bus that wouldn't always start with the battery. I noticed it had a place for a hand crank so I had one made. People couldn't believe it when I would pull out the crank and proceed to start the bus. It would always start that way. Maybe because it was a high performance engine or maybe the electric starter would cause too much voltage drop was was why it wouldn't start otherwise.

I used to enjoy driving my old truck with a non-synchro transmission. It took a bit of skill to learn how to "double-clutch". Once you got good at it you could learn how to shift without using the clutch at all. Then I got an old two-ton with a two-speed axle and took it to the next level.

One time the clutch went out in a pickup truck I had. To get home I would put it in gear and hit the starter until the engine fired and I was able to accelerate. The I would do "no-clutch" shifting to get into high gear.

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#44

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/13/2012 1:57 PM

When I worked on a farm they had a version of continuously variable transmission. It was called a "hydrostatic drive". By moving a lever you could select the optimum speed for doing your work. I think this was done by varying the stator in the torque convertor. I had an old Buick that had a variable stator. It worked like a passing gear except the response wasn't instantaneous. When you pushed the pedal to the floor it would take a split second for the engine to spool up but then the power would come out in spades.

Another interesting machine on the farm was the swather (field mower). It had a dual variable belt drive that also functioned as the steering. Pushing the steering column forward and back would control your speed (including reverse) and turning the wheel would steer it. You could crank the steering wheel hard to the lock and it would spin around in one spot. It was kind of a fun machine to drive. I would turn a couple of donuts in the barnyard before I set off to do field work.

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#51
In reply to #44

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/17/2012 1:37 AM

the simplest way for a "hydrostatic drive" is bypassing the motor by a variable valve.

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#45

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/16/2012 9:51 AM

Electric cars use an electric motor for propulsion. When you want to stop, the motor can be used as part of the braking mechanism and then stop turning when the vehicle stops.

Very similar with Steam engines. The steam is either sent to the drive pistons, or diverted back to the boiler.

A transmission is needed in internal combustion engines cannot be started and stopped in this manner, so the transmission is used to decouple the drive from the engine to allow stops.

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#49
In reply to #45

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/16/2012 4:24 PM

Actually, the clutch or torque converter decouples the engine from the rest of the drivetrain.

I could drive all day, starting and stopping in just first gear with my car and never shift again if I wanted.

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#46

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/16/2012 10:12 AM

The ratio between the highest speed that cars and locomotives are required to achieve and the lowest speed they need to reliably run at is around 100 to 1, if we assume 1 mph for reliable parking, and 100 mph as a maximum. A combustion engine typically has a minimum speed of 1000 rpm and a maximum around 5000, for a ratio of 5 to 1. A combustion engine simply doesn't have the required operating range without a transmission to change the gear ratio. Steam and electric engines operate at full torque all the way to zero rpm, so they don't have a minimum speed, and thus a single gear ratio can always be selected to drive the vehicle at whatever range of speeds is required.

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#47

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/16/2012 10:18 AM

Steam and (electric) motors are powered with a constant pressure (voltage), and "thottled" with volume (frequency, pulse width modulation). Therefore, torque is constant throughout the entire range of motor speed.

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#48

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/16/2012 11:46 AM

Electric motors and steam engined develop maximum torque at no RPM. However, a

steam locomotive can only move a train by using the slack in the couplings to allow the locomotive to break the inertia and get the train rolling. The locomotive goes into reverse slowly and gets all the coupling slack to accumulate before pulling forward. An electric car can get an improvement in range and performance with a gear train or transmission. I spent 13 years testing electric vehicles for both highway and industrial use and found that a gear reduction system was of definite advantage.

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#53

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/17/2012 1:49 PM

Steam and slectricity are secondary forms of power, and the steam engine the power generator or boiler are primary, or the electric motors are the way to transmit their power. Where fuel driven engines use a primary source of power the engine is the seconday with the transmission is third phase of power transmission that makes the power created useful.

Steam engines deliver their torque as that third phase, capable of individually useful power. They are the transmission, and not at all lost.

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#59

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/23/2012 12:07 PM

Electric cars and steam locomotives use External Combustion Engines which has no need for a transmission. computers and wheel based motors replace that application. The Transmission is replaced by electric motors that are set and attached to each wheel and connected to computer in car which tells it what to do when the operator is steering the wheel. With a steam locomotive, they have a reversible electric motor which goes either in forward or reverse.

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#61

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/24/2012 3:34 PM

Electric motors and steam engines develop maximum torque at zero RPM whereas internal combustion engines produce maximum torque at several thousand RPM.

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#62

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

10/30/2012 9:56 PM

A steam locomotive does not need a transmission because the steam engine works well at a standing start, and produces almost full torque at a stall. Some electric cars don't need transmissions because some types of electric motors produce high torque at stall. But some types of motors work better running a bit faster.

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#63

Re: The Case of the Lost Transmission: Newsletter Challenge (October 2012)

11/02/2012 2:33 AM

Somewhat surprised to see no discussion between horsepower and torque. Torque is merely twisting force on a shaft. Horsepower is time rate of doing work, and work is force times DISTANCE. In an internal combustion engine, with a transmission, full horsepower is available in several overlapping speed ranges, so the graph above is really pro-electric spin, since the electric motor can't develop full horsepower until it gets up some rpm. Of course, massive start current can compensate for the tall gear ratio in cases where it doesn't kill the batteries. But the motor will make high-rpm noises, as mentioned before.

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