3 speed transmission for D-fab Trackmaster dozer

Trackmaster bulldozer Transmission rebuild 02 – restoration, cleaning, fabrication

The transmission mechanicals were surprisingly not that badly damaged. It did take an enormous amount of elbow grease to clean all of the grimy oily emulsified yuck off of and out of everything. After cleaning, inspection, polishing, identification of replacement components and so on took place.

Parts laid out from the transmission rebuild. I take a lot of photos so I can reassemble everything. It’s a good way to take anything apart, take all the photos you can.

A bit about what I know about this transmission after taking it apart and studying it. I could find ZERO information online, and I write this stuff up in hopes that it helps someone in the future.

The 3 speed transmission is a symetrical standard splined shaft transmission using sliding standard spur gears. There are two shift forks, and two movable sliding gears. One gear only has one position, the other has two locations. It is a very simple and robust transmission design, with nothing broken and no unbearable wear or damage despite it’s poor condition when I took ownership.

Shafts, splines, sprockets, snap rings are all standard ANSI and SAE. Only the bearings are metric 6000 series items. The three gear reductions of the tranmision are 1.5:1, 4.5:1, and 18.5:1. These are counted manually by turning the input shaft and counting after rebuild and can have a bit of innaccuracy.

The main output shaft is 13/16″ for the 16 tooth sprocket for #60 chain. The bearing on the main shaft is a standard 6305 with bearing dimensions 25x62x17mm Deep Groove Ball Bearing. All of the other bearings, 7 in total, are the same and are 6203 Bearings with dimensions 17x40x12mm. There is one oil seal on the output shaft. This oil seal is an old out of production part: Chicago Rawhide Oil Seal 8774. A modern replacement oil seal I found was a SKF 8796 LDS & Small Bore Seal, R Lip Code, CRW1 Style, Inch, 0.875″ Shaft Diameter, 1.624″ Bore Diameter, 0.25″ Width . I ordered this, and then found an original NOS part on Ebay and ordered that as well. Both have the same dimensions and basic design.

One thought on “Trackmaster bulldozer Transmission rebuild 02 – restoration, cleaning, fabrication”

  1. I’d like to have the part number for the hydraulic motor off of the transmission or information to get one. I need it for mine.

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