Posted by Clint Dixon on Friday, November 21, 2003 at 4:08PM :
I have a multi-part question. Here goes:
I have been using 1940’s vintage hydraulics to power my Good Roads snowplow for several years now. Monarch supplied these pumps and valves to various snowplow manufacturers from the 1940’s through the 1970’s. They no longer service or provide parts for them.
These systems were known variously as Monarch Hy-Lo Jack, Hy-Lo Jeep, and Dyna-Might Electric, among others. The one I am using on my ’47 WDX is a Hy-Lo Jack and is v-belt driven. These pressure pumps are rated at 1500 PSI and have an internal relief valve. I have been told this places them at the higher end of the category that defines them as a “low pressure/high volume pump”. The pump is basically constructed of three flat plates, sandwiched together. The center plate is bored through and houses the helical cut gear set that mesh together and turn to move the fluid. These gears produce a lot of friction at their sides where they contact the two end plates. This creates wear and a loss of pressure. I do not believe there would ever by any noticeable pressure loss because of normal wear in the gear teeth in a pump of this design. Surface grinding all three plates, and the sides of the gears, brought my worn out pump back up to a performance that easily lifts the 1000lb. snowplow along with the entire front of the truck to relieve weight from the front leaf springs. I ground the gears .0003 (3 tenths) narrower than the width of the center plate, so there is not much clearance at the sides. No gaskets are used, These plates just bolt together surface to surface.
An old cast aluminum reservoir that came with one of my pumps indicates to use SAE 10-weight oil for the system. I have been using 10-weight hydraulic oil. I recently ran across some original Monarch literature from the late ‘70s that specify SAE 10W30 motor oil for use in these systems. The cylinders that are powered by this pump and valve are of both the piston and pistonless design. Both have o-rings instead of packing in the glands and the piston styled one has an o-ring there also.
My first questions: What would be the pros and cons of using SAE 10 or SAE 10W30 motor oil instead of 10W hydraulic fluid? I have found that I sometimes have to speed up the engine in warmer weather to get the desired speed in plow lift. Both the driven v-pulley on the pump, and the driving v-pulley added to the stock generator pulley are the same diameter, so the pump is in effect always turning the same speed as the generator on which it clamps and mounts to. Which oil/fluid would better lubricate the moving parts with the close tolerances that these pumps have? How the issues of temperature, foaming, and lubricating of the rods, bores, and o-rings of the cylinders?
Next questions: I have a desire to use one of these pumps to provide hydraulic pressure to the rear of my truck. I would really like to run hard lines along my frame rails rather than hoses the entire distance. I am concerned about heat, chafing, and rock damage. I envision something like what is found on an excavator, only I need nothing larger than .250 I.D. lines. I imagine something like large brake lines. But, I do not want the expense of something I have to pay the local Parker store to bend. Are there any possibilities, or should I just stick with hoses?
Thanks in advance for any input. Maybe I can return the favor someday.
Clint
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