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Farmall Tractors Discussion Board |
Re: M hydrolics
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Posted by john d on August 16, 1999 at 09:40:25 from (206.141.74.34):
In Reply to: M hydrolics posted by George Madison on August 16, 1999 at 07:16:27:
All three ports are pressurized when the lift is operating. This system is designed for single-acting cylinders, where gravity returns the implement to the lowered position. Therefore, you only need one line to each cylinder, but the cylinders must have a "breather" plug in the other end which allows air in and out as oil goes in and out of the other end. The right-side port and the front left port are plumbed together. The left rear is a "delayed action" port which may be used separately. This system was designed to lift the front gangs of mounted cultivators with the front ports, then the rear port would lift the back gang at approximately the same place at the end of the row. When the lift lever is pulled, pressure goes to the front ports first. When the cylinders have totally extended, pressure is then transferred to the rear port. (Actually, if there is a lot of resistance in the front circuit, and not much in the rear, the system can be fooled into pressurizing the rear port before it should.) When both ports have lifted their loads, pushing the control rod half way down releases the front ports, pushing it all the way down releases pressure on the back port. Thus, front ports are always first to lift, and first to release. Pushing the lever to the first detent position without going all the way down may require a little practice, especially if some wear and tear has developed in the system. When the control rod is in the lowest position, no pressure reaches the cylinders. Therefore, implements may move up and down freely. (Remember, no DOWN pressure with this system unless you want down ONLY!) When little pin on the underside of the control rod is hooked over the top of the bracket, the system holds whatever oil is in the cylinders so it can't return to the reservoir. Oil returns to the reservoir by flowing back through the same port it came out of whenever the control rod is all the way down. If two-way action is desired from a cylinder, you need another valve which receives pressure and directs it to whichever end of the cylinder you want pressurized. These came as an attachment on lots of late model M and Super M tractors. It was affectionately known as a "christmas tree" and mounted on the top of the fill port to the reservoir. This system used the original control rod to supply pressure, and the valve control rod to determine direction. This was NOT a live-power system, merely two-way. If you use the system to run a hydraulic motor, you'll need to plumb a return line to the top of the reservoir so the pump can provide continuous flow.
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