TOW TRUCK PROBLEMS

I agree but I assume that the boom function and other functions are the same as with any hydraulic system.

I am thinking that the slippage when there is any pressure being built up on the system is the cause for the slow flow rate. It isn't a two stage pump by an means so it could be a proper alignment fix the problem.

I've seen this happen with my own equipment where the belt was so loose that it didn't squeal but just didn't transmit the power to the pump.

I am well aware about the gear pump design, the originals used Hydreco or Gresen pumps and these were all bi-directional pumps but that's in the past. I don't have a clue what they use now.

Yeah but a misaligned belt will cause a problem with flow because under pressure even with extending a cylinder will need pressure to move that rod, flow rate will be reduced because of the lack of power to build the pressure up at that flow rate. <<< I think I explained that right??

 

Unless the misaligned belt is slipping, the pump is going to move oil. Its a fixed displacement pump. Pressure is a factor of resistance to flow. The system will only generate enough pressure to overcome the load. More load, more pressure. If there is internal leakage like a blown piston seal or a stuck/weak relief valve, you won't be able to build up enough pressure to move the cylinder with a load on it. Like I said, fix the belt alignment first but then get a gauge on the affected circuits and compare those pressures to their specs. Low pressure=low force.

 

Pump definitely needs to be aligned. You said the claws go out but how well do they return to the position in the pic. Would it take less pressure to pull the rams in and that's why they go out ok? Also wonder if the new fitting that is on the lines at the pump are restricted inside.

 

If you don't have the pump lined up properly new belts will not be good for long if they make any difference

 

This what I mean about hydraulics, they can be pretty hard to comprehend how the fluid behaves. If the belt is slipping like you said a few posts earlier (which I was unaware of until then) then get that fixed first. Lost RPM on a pump means less fluid being moved.