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| The WD/WD-45 pumps were rated at 3400 psi. Anything 3,000 or more was fine. Changing the unloader pressure required removal and disassembly of the pump by adding shims. 4 GPM flow was about it. Higher pressures and less GPM's made the tractors more fuel efficient. I'm not sure what an M-Farmall had for GPM's, but the pressures were only 1200 psi if I remember right. The D-series (14-15-17) were 3700 psi and had a more refined Traction Booster system over the WD-series. The D-19 was still a similar piston pump but was backed down to that 2,000 to 2,200 psi industry standard in 1960. The D-17 IV was also the same new lower pressures with 12 GPM pump flow, as was the 190 and D-21. As for the New Generation tractors (3010-4010) having a closed center hydraulic system, I could never see what advantage it had (it didn't) over a 190/190XT with the open-center triple stacked gear pump. You could lift a plow or big round bale of hay on the 190 with the engine just above an idle and turn the steering wheel with one finger all at the same time. The total flow on those old girls was over 20 GPM compared to Deeres 12 GPM. Anyway............what's so great about closed center in the 1960's ?? I just could never see it. One last true hydraulics story. In 1979 I had an old customer that wanted to pickup big round bales of hay with his 1959-60 D-17 diesel and just couldn't quite get it done if the bales were a little heavier than usual. I think 1800 lbs at the time. He had a homemade bale lift made for the snap-coupler hitch and the bale's were positioned right up against the rear wheels and fenders for max lifting power. Plenty of front end weights were there too. I dropped his pump out of the belly and gave it the "plenty of extra shims" repair. I think my test gauge would read right at 4200 psi. When he came and got the tractor I told him to be careful and not let the pump hammer for any length of time. He assured me he'd be careful. A couple weeks later I saw him and asked how the hydraulic pump was working. He smiled and said he idles the engine, the bales get lifted and when the lift arms hit the top, the engine usually stalls. He said it works perfect !! | |
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wd 45 Allis Chalmers hydraulic pressure question/ HOW much PSI did they put out?
