Trenching Attachment


PostcardAuburn Machine Works Inc. in Auburn, Nebraska must have been pretty proud of their latest Jeep-A-Trench model when they had it photographed in front of their plant for this colorful advertising postcard. It's mounted on what appears to be a shiny new late-1950s CJ-3B.

(Note that although the postcard may be hand-tinted, the color looks accurate enough that it does raise the question again of what years Willys may have offered body-color wheels on the CJ-3B, rather than just black or white wheels.)

Installation manualThe Jeep-A-Trench trenching attachment seen on the postcard above was indeed a significantly improved model, compared with the earlier version seen mounted on the back of a CJ-2A in the installation manual at right. In fact, that was one big difference: the early Jeep-A-Trench was attached to the back of the Jeep, while the new "Gear-Draulic" model had much of its weight inside the body, an obvious advantage. Power for the new model actually came from the front PTO rather than the rear.

Randy Brown took a photo at the Jeep Employees Car Show in Toledo of a Jeep-A-Trench mounted on a CJ-3A (30K JPEG). This Jeep is owned by the Historic Civilian Jeeps Collection of Jim and Peg Marski. Jim comments that "it has 9800 original miles and works quite well -- it will dig up to 6 feet deep. Besides the top-of-the-line Jeep-A-Trench (there were 2 or 3 different models), it is equipped with the Auburn Pent-A-Bit system allowing use in rocky soil. It also has a dozer blade, Monarch pump, governor and capstan winch, as well as an aluminum halfcab."

See also a brochure for the early Jeep-A-Trench (50K JPEG) and a postcard showing a CJ-3A (160K JPEG), both with the boom in digging position, and the augers moving loose soil away from the trench.

Jeep-A-Trench "Gear-Draulic"

Hydraulic boomAuburn later produced a booklet advertising the new Gear-Draulic model, with a series of detail photos showing it mounted on a CJ-3B. See a larger copy of the page at left (150K JPEG) describing some of the details.

The booklet goes on to describe other features:

Weight Distribution

"An accomplishment in design permits the installation of the new Jeep-A-Trench Gear-Draulic well forward in the Jeep body over the frame. Moving the center of gravity ahead places more weight on the front wheels, making for more stability and better traction for straighter trenches, and greatly improves steering and roadability between jobs. Being designed, engineered and manufactured in our own plant assures the purchaser uninterrupted parts service."

Transmission of Power

"The engine power is transmitted through a new gear drive connected to the Jeep front power takeoff, supplying power to the digging ladder. By this unit the hydraulic pump for the operation of the boom control is driven, and power is also supplied to the hydraulic drive for the trenching speeds. This compact drive being constructed with helical and bevel gears mounted on anti-friction bearings and running in oil, replaces a multitude of sprockets and chains, as well as the Jeep Rear Power Takeoff and the Jeep Belt Pulley Drive."

Cover page

Speed Reducer

"Our own specially designed speed reducer has a nickel bronze gear and ground steel worm mounted on anti-friction bearings in an oil tight case, and is driven by the variable speed hydraulic drive."

Hydraulic Drive

"When trenching, the power for the forward speed of the Jeep-A-Trench Gear-Draulic is supplied through an exclusive hydraulic drive. By adjusting the operating control, speeds are infinitely variable from zero to the fully engaged position. The hydraulic drive oil cushions the shocks when intermittently changing soil conditions are encountered, making for smooth and precisely controlled propulsion under all conditions."

See all six pages of the booklet (150K JPEGs):


Tremaine Cooper photographed a CJ-3B with a Jeep-A-Trench Gear-Draulic (50K JPEG) evidently still in use by Krippners Trenching in New Zealand in 2003.

Elsewhere on the web, Ronald Cook has some detail photos of an early Jeep-a-Trench on a 1948 CJ-2A.

By the way, Auburn Machine Works, established in 1926, is still in operation as Auburn Consolidated Industries, making earthmoving and agricultural equipment.

Thanks to Gary Keating for the GearDraulic postcard and brochure. Also thanks to Alden Jewell, Tremaine Cooper, Bob Stewart, Dave Christians and Randy Brown. -- Derek Redmond

See also a Jeep-A-Trench mounted on a CJ-5, in a catalogue of Jeep Specialized Vehicles and Equipment.

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Last updated 26 October 2008 by Derek Redmond redmond@cj3b.info
All content not credited and previously copyright, is copyright Derek Redmond