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Rack and Pinion

04/05/2012 4:23 AM

Can someone please help me, I need some help for a rack and pinion set up I want to use on a machine.

I will be using the rack in a vertical position to raise and lower a load. The load will be at the max 20 000kg

The load will travel 10 meters and will need to operate for a continuous time of 0 to 6 hours.

I will be using a pinion gear with a diameter of 380 mm or 1.193 meter circumference.

The planetary gear reducer and hydraulic motor combination will produce 52 rpm at max.

I did a sum of 52 rpm x 1.193 circumference to get a travel speed of 62 meters per minute.

I will be using 2 planetary reducers side by side each with 24 000nm of torque.

To give use a run down on my machine when in normal use it will be pushing a load to a max of 10 000lb at an average of 10 meters per 20 minutes, but will also be required to run up and down at full speed/load for a max of about 6 hours.

Based on all this could someone please help me with the calculations to work out the correct module for my rack and pinion to handle the conditions and load of my machine. Thanks for you time. Dan

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#1

Re: Rack and pinion

04/05/2012 5:24 AM

Do you have a drawing?

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#2
In reply to #1

Re: Rack and pinion

04/05/2012 6:27 AM

I can draw up a rough one for you, Ive been waiting untill I got all the dimension on parts I will be using so I can draw up a scaled version. cheers Dan

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#3

Re: Rack and Pinion

04/05/2012 11:38 AM

You say The load will be at the max 20 000kg... and then later you say: it will be pushing a load to a max of 10 000lb

Well, Which is it?

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#4
In reply to #3

Re: Rack and Pinion

04/05/2012 8:39 PM

Its for a drill rig, when you are drilling rods into the ground you use a pushing or feed force of 0 to 10 000lb depending on ground. Each drill rod weighs about 350kg, once you have drilled down to the maximun depth of the machine ( in my case 300 meters ) you need to be able to pull the drill rods out of the ground. 300 meters of drill rods, plus the drill bit and drag on the drill rods that equals the 20 000kg I am refering to. Dan

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#5
In reply to #4

Re: Rack and Pinion

04/05/2012 9:46 PM

Something like this....

TECHNICAL SPECIFICATIONS

CAPACITY

6" to 8" dia bore holes to a depth of 300 mtr (1000 ft)

PRIME MOVER

Truck mounted rig with power from truck engine through transfer gear box

WORK METHOD

Rotation with direct circulation, nucleus destruction with bleeding by water,
air or foam
Drilling by drag bit (over burden) Roto percussion with DTH hammer

MAST

Box type structure
Max Capacity - 15 tons ( 33000 lbs )
Height - 8.1 mtr ( 27 ft )
Rod handling capacity - 6.1 mtr ( 20 ft )

HYDRAULIC OIL COOLER

Fin type, Flow capacity 90 GPM Cooler fan drive through hydraulic motor

PULL UP AND PULL DOWN

By hydraulic cylinder and wire rope, Reeving Ratio 1:3
Max pull up force - 9200kgs (20240 lbs )
Max pull up speed - 37mtr/min ( 122ft /min )
Max pull down force - 6318kgs (13900 lbs )
Max pull down speed - 53 mtr/min (175 ft/min)
HYDRAULIC SYSTEM210 kg /cm

2 (3000 psi )

ROTARY HEAD

Rotary head is powered by one hydraulic motor
Max torque - 303 kg - mtrs ( 26,400 in - lbs )
Max speed - 0 to 130 rpm
OPTIONAL ATTACHMENTHydraulic motor driven screw type mud pump

JACKS

Four hydraulic jacks of 90 x 56 x 795 box type

WATER INJECTION PUMP

Triplex reciprocating pump of 50 lpm 1000 psi powered by hydraulic motor

BREAK OUT WRENCH

To open the drill joints hydraulic break out wrench of 350 mm stroke
will be provided

ROD CHANGER WITH AUXILLARY WINCH

Manually operated single pivoted rod changer with 1000 kgs capacity pull up
winch to carry drill pipes, castings and hammer tools

SUITABLE COMPRESSOR

900 cfm, 200 psi / 1100 cfm, 300 psi
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#6
In reply to #5

Re: Rack and Pinion

04/06/2012 1:06 AM

Yes mate, same thing. Mine will have some different spec to that though the basis is still the same.

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#7

Re: Rack and Pinion

04/06/2012 5:59 AM

The environment where this will be used is full of grit and mud. Why are you proposing a rack and pinion for such conditions? Wear will be a major problem, in field conditions with little or no maintenance facilities. The specification attached to the photograph implies a 6" bore 7' stroke hydraulic cylinder (gives 40% over capacity) to do the same task. Much cheaper than a 21' rack, pinion, gearbox, and hydraulic motor, but simpler and easier to maintain. Any calculated value of module size would have to be at least doubled to take into account your operating conditions. Your competitor has a better design.

Your continuous time of 0 to 6 hours is misleading. You have to stop every 20' to attach or detach a rod. This means stop, unclamp, drive unloaded to the other end of the travel while a rod is added/subtracted, stop, reclamp, restart. All the time the drive is stopped oil will be directed back to tank via an open centre valve, creating heat but doing no work. It gets worse if you intend to operate at high ambient temperatures. Hot oil affects the performance of a hydraulic motor to a much greater extent than a hydraulic cylinder. Your competitor has a better design.

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#8
In reply to #7

Re: Rack and Pinion

04/06/2012 6:40 AM

Your brought up some interesting points.

1. yes environment is not on my side bud can be eliminated by some sort of guarding ( same as on a mill for example.

2. The machine in your pictures only has a pull force of 20 000lbs, I need 20 000kg. The 6 to 7 inch bore implies to the size of hole the machine can drill not the hydraulic cylinder bore size. To get 20 000kg out of a cylinder I will need ether 2 smaller ones or 1 very large diameter one which will not fit in with my machines design.

3. A typical cylinder over rope design is basic as you say, but as for wear, take into account the following

1 cylinder

1 travel block with 4 sheave wheels with bearings or sprockets with bearings

2 upper sheave wheels/sprockets with bearings

2 lower sheave wheels/sprockets with bearings

4 sets of chains or wire ropes

And the maintenance that goes into these, time to replace and the amount of spares you need to carry all add to $$$$$.

Also it is a good practice to replace all the above item ( except for the cylinder ) every 12 months and cylinder every 24 months.

2 planetary gear boxes, with hydraulic motors, brakes and counter balance valve cost around $25000 a pair and take little time to replace.

Yes cooling in something I will need to look at as well as wear factors on the rack systems ( which is something I am still working on and no little about that is why I am still in the design stage ).

But ether way I would still like to no how I would go about working out the formula and you odviously no a bit about the wear factors so what sort of life do you get out of a rack and pinion set ( or how could one work that out ). cheers Dan

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#9
In reply to #8

Re: Rack and Pinion

04/06/2012 1:50 PM

So more like this...

TECHNICAL SPECIFICATIONS

CAPACITY

6" to 12" dia bore holes to a depth of 605 mtr ( 2000 ft )

PRIME MOVER

Truck mounted rig with power from truck engine through transfer gear box
or through a separate deck engine

WORK METHOD

Rotation with direct circulation, nucleus destruction with bleeding by water,
air or foam
Drilling by drag bit (over burden) Roto percussion with DTH hammer

MAST

Box type structure
Max Capacity - 30 tons ( 66000 lbs )
Max height - 8.18 mtr ( 27 ft ) or 9 mtr ( 29.7 ft )
Rod handling capacity - 6.1 mtr ( 20 ft )

HYDRAULIC OIL COOLER

90 GPM fin type Cooler fan drive through hydraulic motor

PULL UP AND PULL DOWN

By means of twin hydraulic cylinders and wire rope, Reeving Ratio 1:3

MAX PULL UP FORCE

Max pull up force - 18410 kgs( 40,500 lbs )
Max pull up speed - 40 mtr/min(132 ft/min)
Max pull down force - 12635 kgs ( 27800 lbs)
Max pull down speed - 60 mtr/min (198 ft/min)
HYDRAULIC SYSTEM225 kg / cm

2 / (3200 psi)

ROTARY HEAD

Rotary head is powered by two hydraulic motors
Max torque - 606 kg - mtrs(52800 in - lbs)
Max speed - 0 to 175 rpm

JACKS

Four box type hydraulic jacks of 125 x 70 x 795 mm stroke

WATER INJECTION PUMP

Triplex reciprocating pump of 100 lpm 1500 psi powered by hydraulic motor

BREAK OUT WRENCH

To open the drill joints break out wrench of 350 mm stroke will be provided
with rope attached

COROUSEL ROD CHANGER

The pivoted corousel rod changer with 6 rods handling capacity, hydraulic
operated swing cylinder arrangement and which of one ton capacity to carry
drill rods, casings and hammer tools

OPTIONAL ATTACHMENTS

Welding machine, mud pump, diesel filling pump, skid platform with deck
engine, box type jack automatic rod handling arrangement to handle 50
numbers of 20ft drill rods with remote control

SUITABLE COMPRESSOR

1100 cfm /350 psi, 1150 cfm / 300 psi, 900 cfm / 350 psi, 1100 cfm / 400 psi

SPECIAL ATTACHMENT

Automatic rod handling arrangement to handle 50 numbers of 20 ft drill rods
with remote control

TWO TRUCK ARRANGEMENT

One for rig unit and second to carry the compressor
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#10

Re: Rack and Pinion

04/06/2012 2:19 PM

Hydraulic systems have the advantage of being self lubricating. All of the other parts you listed have the ability to be fitted with an automated lube system. (Vogel, or SKF brands).

If you are determined to use a rack and pinion, you may need to construct it yourself. Use Global as a search site for gear manufacturers. You will likely need to join multiple sections of straight gear racks. And then select a pinion gear and drive system to drive it. The gear manufacturers would be more familiar with the process of setting this up. They are the specialists.

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#11

Re: Rack and Pinion

04/16/2012 7:04 AM

The choice of a pair gear + rack is not at all (whatever you bring as arguments) for this application. I say that knowing from a several years design activity in earth drilling machines what are the problems of this activity. You totally neglect the flank wear which will lead to heavy shocks and variations of the force on the tool which in turn will reduce its life expectancy.

Why do you not think about chains (multiplex) ? To change a chain is a simple operation and the same for the sprockets. Wear will not be so intensive since sliding is in the bushings which are more protected against ingressions as an open rack. On the sprockets wear is only generated by the pitch increase due to bushing-pin wear. The sliding occurs only when under load the chain links rotate to each other i.e. only when the pair comes at the sprocket.

I think that your economical approach is correct but you did focalize on only one solution and you should look at more.

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