Todd Hydro Inspector Cleaner Loader.

[DrWazzock]

The elevator extension lift Rams (single acting) were leaking so I am having them reconditioned. The spool valve that controls them was seized up but I managed to carefully free it off. It didn't end there though, it never does. I noticed the oil supply to them isn't entirely switched off by the spool valve when the spool valve is in neutral position. Is this to keep them under pressure while the machine is running, thereby helping support the elevator or is it (more likely) that the spool valve is knackered. With the engine running there is slight flow to the Rams unless the hydraulic motors are taking the oil by operating their control valve earlier in the block. Another mystery is that the spool valve that controls the Rams is prevented from going to the dump position by a screw (which looks original ) in the end of the spool valve lever housing. So how do you let the Rams down? Presumably when the pump stops the pressure leaks back even when in the neutral position so maybe it's not a leak, but intentional and would let the Rams down slowly provided you have taken the locking pins out while the engine was running and maintaining pressure.

Thanks in advance if anybody can shed any light on this. I will try Terry Johnsons in the morning.

 

[DrWazzock]

To partly answer my own question, there seems to be a fair amount of back pressure on the return to tank through the filter. This back pressure looks like it is finding its way to the Rams via the leaky spool valve. I think it will reduce the back pressure when I change the filter, and reduce the leakage pressure getting to the Rams so it's not a serious problem. There leakage flow to the Rams supply pipe but no serious pressure.