Cable Shift Transmission

Two cables... you can't push with a cable.
It also depends on the type of gearbox (assuming you mean gear shift? I only people would write more explicite Qs and stop assuming we are mind readers)
A constant mesh gearbox as was used on Vespa & Lambretta scooters has a simple linear motion, thus a push-pull cable system worked fine.
Del

Electropneumatic shifting is used on longer vehicles, particularly those where the engine is at the rear, like buses.

thanks to both of u... and very well i meant gear shifting!!!... sorry if i was not clear... but i want to know how cable shift is effected in passenger cars?... how is it advantageous over conventional(linkage) shift?

its easier to route the cables from the interior to the g/box thus cheaper.

and easier on assembly lines

These days, in passenger cars, the rod linkage is no longer "conventional". Cable shifting is the norm. A cable provides for more effective decoupling of engine motion from shift lever motion. This is especially important in transverse mounted engines, where the entire engine and transaxle assembly rotates in reaction to torque.

In the old days of longitudinal engines and rear wheel drive, floor shifters were anchored to brackets on the transmission itself. The action and reaction forces could be transmitted by short rods, with there being no need to provide for changes in distance between actuating and actuated levers. In many modern cars the direction changes required to get from shift lever to transmission (while also accommodating engine motion) would require a complicated, sloppy linkage.

Honda cars have long been praised for their excellent shifter feel, which comes from their well-designed cable setup.

Look under the hood of a modern car and visualize the complicated rod linkage required to replace a cable. Remember that modern drivers expect the shift lever (whether for automatic or manual) to remain stationary once a gear is selected. With the engine vibrating (and moving from torque reaction) it would be difficult and costly to make a rod linkage work well.

Cables replace the function of the solid linkages.

You can have just two cables, as cables can "Push" as well as "Pull. (sorry Del)

The "Bowden" cable is this type of cable (there may well be a hundred other names out there, but this is one I know of).

They are a relatively stiff cable, generally with a solid steel rod as the end part of the cable. The end of the outer sheath has a steel tube in which the solid end of the inner slides, hence the ability to pull AND push.

As a general rule, one cable provides the fore and aft movement of the gear lever position, while the other cable provides the sideways (or left/right) axis of the shift lever.

Types of shifting...(some previously posted above)

Cables

External linkages

Direct (where the shift lever is bolted direct into the gearbox)

Pneumatic (air shifting - lots of trucks/buses use this)

Hope this helps

Cheers

Tony

Yeah, ok I know you can push, a bit, but obviously you can transmit more force more reliably pulling.
In push mode are you actually shifting the gears or just shifting an actuator valve of some sort?
My frame of reference was old scooter gearboxes which are rather out of date I expect.
Still see a few restored ones round here in the summer... ah the sound of a Lambretta <sigh>. Pretty girls in mini skirts sitting behind you <sigh sigh>... and then they climb off <flump thud>
Del

Ha HA, like your ramblings...

The ones I've seen do push. Say pull for the 2 & 4 position, push for the 1 & 3 position, & the second cable would pull for the left (1/2) gate, & push to go to the right (the 3/4 positions) Obviously this relates to a std 4sp H pattern.

But, YES I have seen 4 cable setups where each cable only pulls.

See ya.

Ahhh yes :-) Back in the day <---way back...when I was studying industrial arts in college I had a Lambretta...we used it as a "project vehicle" in our Automotive class. When we were done we had over 200cc and it would really move! (..and yes the girls loved it! till they got dumped off the back!) Oh the memories you bring to mind Del!

In push mode are you actually shifting the gears or just shifting an actuator valve of some sort?

The cables (left right and back/forth) can replicate the motions of a rod linkage. In a historically simple rod linkage, that on the air-cooled Beetles, a single rod pulls in and out of the front of the transmission when the lever is moved back and forth. When the lever is moved from side-to-side, the rod rotates. On the end of this rod (or literally an extension of this rod) inside the front cover of the trans, is a Framitulator assembly in which the Verbenflitzer (an L shape on the end of the rod) engages in Schlottenthingys on one of three shift rods which move fore and aft, and which are detented, each into drei (3) Klickenpozition. One of these rods selects between engaging first or second, another third and fourth, and another, reverse. Each rod has a neutral position. If two rods were simultaneously moved out of their neutral positions, Boomenschmashen (bad thing) occurs. These rods do not actually move gears around; they move Synkronizerringen (synchronizer gizmos) which lock an otherwise Freeveeling gear to its shaft, after having first sped up or slowed down the gear to shaft speed, to prevent Grindundklasshning.

In a cable operated-trans, the cables duplicate the shift rod functions, acting on the Framitulator in the same way that a rod would (or could... there are all sorts of articulation methods).

Going back to the power boat usage, when a push-pull cable is used, the operator cannot detect whether the mechanism pulls to go left and pushes to go right or Wisenwersa.

Thanks, that's cleared that up.
Of course I recognise that it must be adjusted for optimal tension on the decravinating washer where the toggle spline grunge pin thrust bearing slides through it.
Del

Yes, absolutisimally.

Thnx to all the contributors... all posts were helpful and informative.. wish to study in detail about these mechanisms about how these linkages are constituted or cables routed in an actual set up.. will get back to this thread when i get some doubts... also if anyone has got any links that has got block diagrams or sketches related to the above pls post them... Thnx again!

Cables will likely be push-pull type for transmission shift. Manual transmission might require two cables to transmit both back/forth and lateral motion. A simple mechanical linkage assembly is usually required at either end of the cable. They are every bit as good as a linkage shift mechanism, but more flexible and more versatile. Manufacturers are now considering electromechanical systems as an alternative. For cables, see: http://www.tuthill.com/us/en/products/Catalog/Custom-Assemblies-Push-Pull-and-Pull-Only.cfm