Leroy’s Power Steering Hydraulic Dump Bed Conversion

By The Mother Earth News Editors
Published on January 1, 1985
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Leroy Richter's
Leroy Richter's "Power-Steering" Dump Bed is impressive and extremely useful.
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The twin cylinders are pin-mounted to a length of angle iron bolted to the chassis rails.
The twin cylinders are pin-mounted to a length of angle iron bolted to the chassis rails.
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The bed frame is constructed of 3-, 4- and 5-inch channel iron. Note the pipe-and-channel rear hinge setup.
The bed frame is constructed of 3-, 4- and 5-inch channel iron. Note the pipe-and-channel rear hinge setup.
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Leroy Richter's
Leroy Richter's "Power-Steering" Dump Bed is impressive and extremely useful.
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The two-way tailgate.
The two-way tailgate.
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Using this formula and the diagram in the previous image, you can roughly calculate any homebuilt system's maximum capacity.
Using this formula and the diagram in the previous image, you can roughly calculate any homebuilt system's maximum capacity.
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The cylinder mounting angle is critical because it affects both the payload capacity and the maximum tilt of the bed. The diagram above can be used to roughly calculate any homebuilt system's maximum capacity, using the formula in the following image-gallery image.It may look complicated, but figuring it out is simply a matter of establishingA, the distance between the bed's rear hinge pin and the cylinder's upper mount;B, the distance between the bed's rear hinge pin and the front of the bed;X, the length of a line parallel to B, measured between the cylinder's lower mounting pivot and the line's intersection with...Y, the distance perpendicular to A and X, between the upper cylinder mount and X;R, the radius of the pistons within the cylinders;P, the maximum operating pressure of the power-steering pump (most are limited to about 1,500 psi with an internal dump valve).Note that the rear hinge posts must be at least 2 inches forward of the bed frame to allow clearance at maximum lift.
The cylinder mounting angle is critical because it affects both the payload capacity and the maximum tilt of the bed. The diagram above can be used to roughly calculate any homebuilt system's maximum capacity, using the formula in the following image-gallery image.It may look complicated, but figuring it out is simply a matter of establishingA, the distance between the bed's rear hinge pin and the cylinder's upper mount;B, the distance between the bed's rear hinge pin and the front of the bed;X, the length of a line parallel to B, measured between the cylinder's lower mounting pivot and the line's intersection with...Y, the distance perpendicular to A and X, between the upper cylinder mount and X;R, the radius of the pistons within the cylinders;P, the maximum operating pressure of the power-steering pump (most are limited to about 1,500 psi with an internal dump valve).Note that the rear hinge posts must be at least 2 inches forward of the bed frame to allow clearance at maximum lift.
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This bracket-and-pin mount on the bed crossbar is typical of all the cylinder pivots.
This bracket-and-pin mount on the bed crossbar is typical of all the cylinder pivots.
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The control valve is mounted on the inner fender, next to the overflow reservoir.
The control valve is mounted on the inner fender, next to the overflow reservoir.

As anyone who owns one can tell you, a truck’s a mighty handy vehicle to have around. The trouble is, once you’ve stuffed it to capacity, you eventually have to face the prospect of shedding the load, and, no matter what you’re hauling, that always means work.

Often (especially when the cargo is gravel or manure) that particular task is one most folks would rather let someone else do. Well, our Eco-Village director, Leroy Richter, has discovered a willing “volunteer” that’s available every time he cranks his rig over: the truck’s original power-steering pump.

That’s right! Unlikely as it sounds, Leroy has successfully tapped the force supplied by that commonplace factory-installed component and directed it to a pair of hydraulic cylinders mounted to his vehicle’s chassis. By engaging a control valve from inside the cab, he can activate the pistons which push the rear-hinged truck bed upward, dump the load and then reverse the valve to force the double-acting cylinders and bed back down against a pair of stops. It’s simple, it works, and it cost him about $500 in materials (including a new bed!) and a full week of work to complete. Let’s take a look at Leroy’s hydraulic dump bed conversion.

Dump Bed Conversion Basics

The dump bed conversion project started a year or so ago when Leroy purchased a utility company’s 1975 Chevy ¾ -ton fleet truck at auction for $1,095. Though mechanically sound, the vehicle’s sheet metal needed repair, and the service bed had been removed, leaving a bare chassis. His first step, then, was to obtain a bed and work up a reliable hinge mount for it. Rather than scour the wrecking yards for a conventional pickup box (which would have been expensive and somewhat limited in capacity), Mr. Richter opted to fabricate his own bed by using channel iron, square steel tubing and heavy-gauge sheet metal.

Two 95-inch-long sections of 5-inch channel serve as the bed’s main structural components, which in turn support six 3-inch cross members: five 80 inches in length and one only 48 inches long (to allow two short bridges to be welded in over the rear axle area). A perimeter frame of 4-inch channel iron ties the cross members together, and 2-by-6-inch gussets at the main rail joints strengthen each junction.

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