big rig transmission

[wangp1283]

Does anyone know the size of a semitrailer transmission gear? (width, diameter)

Do you know the cost of producing such a gear? It seems gears are pretty expensive.

Thanks in advance.

 

[GregLocock]

Tractor gears (which must be pretty much the same size) are about the size of the palm of your hand.

If you are making a million a year of them they cost about $10-20 each to make.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[rmw]

First, heavy duty truck/tractor transmissions (gear boxes) come in all sorts of sizes and configurations. Trailers seldom have gearboxes, but it is not totally unheard of.

Transmission gear boxes also come in combinations as well. A very famous combination in the USA 20-30 years ago was the 5X4, meaning one box with 5 gears in line with another box of 4 gears, with all kinds of combinations therein. 4x4's were also common. Managing the steering wheel, while manipulating a combination of two sticks was sometimes a challenge, since these combinations were often used on other than "over the road" plain vanilla rigs.

Common gear boxes range from the simple 5 speed to well into the double digits. Ten speeds, 13, 15 & 18 speeds are quite common, and some older boxes had more. I seem to remember an older model with 24 forward speeds.

Models come in single or multiple countershafts.

Within the gearbox, individual gears come in all different widths and diameters, depending upon the ratio of that particular gear in the gear train and the amount of torque that that gear was expected to have to transmit.

Therefore the answer to your (somewhat vague) question is a difficult one to handle, but the previous answer given could well fall within the range of what is out there. As noted, cost of producing any item depends upon the quantity produced.

If you have a place of business in your area that rebuilds or remanufactures truck transmissions, visit their shop, and you can see for yourself the immense variety of what is out there.

It has been a long time since I have been involved with that world, but I have mental images of gears from transmissions I was having rebuilt being in the 6-8 inch diameter range, with about 1-1.5" widths. There were smaller gears in the set as well.

rmw