(800) 853-2651
SHOP NOW

Replacing key on front mount hyd. pump?

J

jfharper

Member
The key on my front mount hydraulic pump (3/4" shaft) sheared off and I think it was because the key seat on the mechanical element (drive shaft) has a larger height. The key was a square key, 3/16" x 3/16" x 7/8" (WxHxL). I think the key seat on the drive shaft allowed the key to work itself out until the key sheared off. The shaft on the pump shows a couple chips where the key seat set into...hopefully it is OK.

I was thinking of just getting some key stock that was rectangular, like 1/2" x 3/16", cutting the length I need and then grinding down the height so the key cannot work itself out of the pump shaft key seat.

Question is, should I go with carbon steel or stainless? I want to go hard enough on the steel to handle the torque, but also allow for shearing to avoid damaging the pump shaft if it comes to it. Anyone know or have a recommendation?

My pump is a 1.95 cu in displacement pump, 2300 PSI peak and I have a pressure relief on my valve set to 2150 psi. My tractor is a massey 205 industrial...I have no backhoe, just a 200 davis front loader and 3 pt rear implement with rams for tilting and such. TIA
 
I personally prefer replacing a key, to removing shafts to repair keyways. That is my objection to using harder key stock. I have used key stock that was oversized, for worn keyways, to get a little longer life out of a unit, but in your case I would take the keystock to a machine shop and have a surface grinder plane down one side, rather than try to do it myself with a file or grinder. You will probably need more than one key anyway, and one stick of key stock can yield several keys, so you get more out of the machine shop.
 
Are you saying the keyseat is too long? or too deep? If you measure across the keyseat to the bottom of the seat, for a 3/16" key (.1875"), it should measure 3/32 (.0938) or a little deeper. The average guy doen't have the proper tools to measure things like this but if you have a dial caliper you can check it.

I would be more concerned that the key seat is worn, and if that's the case you'd be better off making a new shaft or welding up the end and having a new key seat cut. Preferably a woodruff key that won't work out. If that's the case then I'd also get a new coupler sprocket, lovejoy coupler, or whatever couples the pump the the shaft.

If there is just a space above the key when the shaft and coupler are together, a set screw above it will hold it down and that's how most are done. Then the key can't wiggle and wallow out the slot, and it stays in place.

Donovan from Wisconsin
 
Both the drive shaft and pump where brand new, only 4 months old before the key sheared.

Yes, the key seat depth in the drive shaft is too deep, thus allowing the key to work itself out.

It would cost more to go to a machine shop than to get a new pump...I think I'll try some steel (not stainless) rectangular key stock and see if I can get it to work.

The key that came out was a rounded edge or feathered square key...it was oversized, and these feathered keys are not suppose to come out or need to be held in place with a set screw. Thanks for the replies and please post more advice if you have it.
 
Have you room to put a jubilee clip around the shaft to keep the
key in place? I have done that many times on milking machine
vacuum pumps, in fact on some where the keyway was worn at the
point where the pulley needed to run, I used a longer key and
tightened the jubilee clip over the top of the longer key, thus
holding it firmly in the unused part of the keyway. Lasted for years.
Sam
 
You must log in or register to reply here.

Similar threads

J
1975 Ford 3550 key on power
Replies
14
Views
253
jrsavoie
J
T
Switch placement?
2
Replies
20
Views
532
Hobo,NC
Hobo,NC
M
PTO pump question
Replies
4
Views
348
mfbengel
M
showcrop
901 front wheel bearing retainer
Replies
5
Views
178
John P.
John P.
R
question for those who know
Replies
10
Views
374
r.w.b.
R
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top