Transmission - Gearbox

Here the transmission is mounted to the lazy axle and the rear power take-off shaft can be seen coming out the rear of the transmission. This shaft on the prototype has a splined coupling to allow the steering clutches to be removed. The shaft on the model has been left in one piece to allow easy alignment of the bearings. The main clutch is at the other end of this shaft.



The aperture at the front of the gearbox is to allow the removal of the gear cluster and sliding gears. The gear cluster mounts to the lower shaft and drives the bevel gear. The panels on the bottom and sides of the gearbox will be fitted after the reverse gear idler shaft has been installed.

Transmission - Power Take-off and Drive shafts

This is the power take-off shaft. It is being reduced with an external hone from 16mm to 5/8" to fit the available bearings. This produces a very high precision, parallel result.







The shaft is mounted in a chuck attached to a dividing head. The spline requires 9 teeth. These are marked in red on the dividing plate.







The splines are cut with a tungsten carbide D bit profiled to the involute section.








The cutter runs at 250 RPM at a feed rate of 25mm per minute.

Transmission - Mounts

The mounts were profiled in the mill. The mount is 25mm high and each cut was about 1.5 mm deep.
This is one of four mounts. They will be brazed to the rear of the gearbox. These sit on the lazy axle.






The matching caps were machined on the lathe and milled to half diameter. They were then mounted on the mill and four recesses milled to receive the bosses which were then brazed on.







Here you can see one of four assembled mounts and the partially completed end caps. The small bosses were brazed on with nickel; bronze.







The four mounts brazed to the transmission housing and end caps before assembly.









The rear of the transmisssion has been bored for the rear power take-off.

Radius Arms and Pivot

These are the arms which run from the middle of the rear axle and keep the tracks parallel. The gearbox will clamp on the lazy axle







Each track can pivot independently from the other on these arms.








The tracks and stone guard have been removed. The rollers and mounts can be easily seen.