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Muncie hydraulic pump for grain truck

3044 Views 5 Replies 4 Participants Last post by  rickfly
I replaced the old hydraulic pump on my 10 wheeler grain truck with a new Muncie pump. It has two pto stub shafts and I'm not sure which one to use. The directions show nothing and there's no casting arrows on the pump. The truck pto turns CCW if facing the shaft, so the pump needs to turn CW. The pump shafts sit one on top of the other. The old pump used the top shaft but it is over 40 years old and was told it was obsolete.
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Do they both turn the same direction or are they reversed? One for cw and the other ccw? Or is one for for a hirghe input speed?
The instructions say nothing regarding the shafts. I'm assuming they're reversed, only because the guy I bought it from said one shaft is CCW and the CW. I asked him which shaft is which and he said it would have an arrow on the pump, but it doesn't.
Is the pump housing shaped fairly similarly to the old one it replaced and that goes for where the two hydraulic ports are located as well. If so and you didn't swap hoses around but kept them in the same orientation chances are fairly good that its going to be the same shaft as previously used. Probably not proper procedure perhaps but if it were me I would just make sure oil is able to run by gravity down into the pump body so its being lubricated and then with the drive shaft on the upper stub, start it up at low idle of the engine and listen for any noises that don't sound right and if none, then try the hydraulic control to see if you get any action. I would think that the worse that could happen is its milling around and trying to push oil into the reservoir but really can't grasp hold of more oil so nothing much would happen.
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With the old pump, it used the top shaft, so I have it on the top shaft on the new pump as well. I'm like you Northern Farmer, I can turn the shafts either way with my fingers, so if I just bump the controls I doubt I do any damage at an idle.
dependent on the input from your pto from the trans, indication of flow direction and suction and discharge of the oil lines, this pump is likely bidirectional , but realistically is designed for one direction. figure out the input direction and note that the flow of gear pumps on the suction side will flow around the periphery or outside of the pump, in other words if when looking at the gears from the suction side of the pump, they should be rotating so as to draw the oil around the outside of the housing , or think of it as the gear teeth separating from each other as you see them. usually the suction side of the pump has larger ports, so if the bigger port is the suction, and when you rotate the pump input in the direction of your shaft from the trans, and the gear teeth are not separating, then you need to use the other input shaft of the pump to change the direction of flow in the pump...
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