I am reassembling the pump cartridge on my #44 hydraulic control, serial no. 9W1692. The pump rotor and vanes have about .005" end clearance between the end bushings when both bushings are tight against the pump ring. There is a shim (part number 9F3184) between the rear end bushing and pump ring that is .002" thick. I was wondering if there is a spec. for rotor end clearance, I can't find one in my manual. Is this an acceptable tolerance or does the pump need more attention? The rotor, vanes, ring, and bushings all seem good otherwise.

The Servicemen's Ref. Book on Hydraulic controls does not appear to mention anything about internal end clearance and bases replacement on pump performance.

I would think the 9F3184 (0.002) shim established the original running clearance.
It may be possible to remove that shim to recover from excessive end clearance
but I can not say that I have done this on a #44 pump. Why don't you give it a try and see if it can be done. Seems like it would be ok if everything is worn on the same plane.

OM, thanks for the reply. I might give that a try and see what happens.

Toby,
Here is some information from the Hydraulic controls service book, these pump cartridges are a basic vickers unit and any decent hydraulic shop should be able to tell you about clearances, if there is wear on the rotor side of the bushings, the bushings can be sanded or ground flat and shims changed to make up for the wear. If the wear is on the rotor, replacement is required, if the ring is rough it can be reground a little.

Thanks for the info, josh. I do have access to some Vickers technical manuals, I might look through them and see if I can determine what some of their clearances are, providing I can find a unit with comparable specs. I might try it a little on the loose side to start with, I can always take it back apart and try something else if it doesn't seem right. It should make for an interesting experiment.

You dont want them too tight because after the oil heats up the pump can tighten up.

Better to be too loose than too tight in your pump clearances. You need enough clearance for lubrication. No clearance, no lubrication. If you sieze your pump due to not enough clearance, big damage will be done before you can get the engine shut down. If in doubt, stay with the .005" clearance that you had to start with. I have the same #44 hydraulic unit on my D4 and I have been through it more than once. The pump has plenty of reserve for blade working. Never work your pump on a low oil level. That will ruin them quickly too. The vanes are the first parts that goe bad on low oil. Been there, done that.

I think I will try the pump with the .005" clearance I already have and see how it operates. I've learned a lot about these between what I've studied and your replies, and it seems these older units did run with more internal clearance than most out there today. Thank you to all who posted on this thread, your knowledge is invaluable.