Some sort of a PTO type device?

Asked Herm. He had no idea.

 

Best guess is that the PTO had a side gear that meshed with the driveshaft gear to move the jeep when the trencher PTO was engaged. Sound good to you? Neat setup though.

 

I realize it's an old post, but since nobody answered;
The ringgear brazed to the circumference of the parking brake drum is the wheel power input gear for the GoFor Trencher machine.
The ringgear is driven by a sliding gear on an intermediate shaft operated by a handle directly behind the driver door cutout. That shaft is belt driven from a Model A Ford transmission sitting behind the driver seat attached to the GoFor frame.

In operation the Jeep transferr case is placed in neutral, and the PTO powers the GoFor. The steering wheel is locked in a fairly straight position, and the digging chain lowered into the ground, with the dirt conveyor running. Once depth has been reached the slider is indexed into the ringgear on the brake drum, the backfill blade is lifted, and the aux wheeldrive tranny is placed into gear to move the machine forward.

Shortly after releasing the clutch the operator can determine if he is in a low enough gear on the aux drive by determining if the jeep is still running. Top speed in sand with a 7" set of teeth in the digging chain cutting sandy ground is 800 feet per hour. Max depth is 4½ feet, and the machine can shift to dig a bellhole at the end of trench.

GoFor also offered air compressors and electric welders (Hobart Bros). The AC and Welder units were civilian adaptations from US Army machines in WW2.

Later delivery machines used the FC 170 full floating rear axel onthe trenchers.
Trenchers were also mounted on IH short chassi 4x4 trucks into the 1970s.

Anybody interested in buying a complete trencher on a 1957 Jeep that needs new frame rails feel free to contact me. Location= Rochester NY area.

 

Those silly guys that drag home trenchers and such. R)

 

Also, this ring gear wasn't brazed, it was a solid cast unit:

 

Looks like they got smart and made a change to a larger toothed gear in later models.

My 57 has a cast ringgear that is shrunk and brazed onto the drum, about 4 teeth per inch.