Case 320 Backhoe

Need to find info on 1956 Case 320W backhoe, we need seal # for the hoe lift cylinder...
We keep blowing seals from local hydraulic shop.
We would like to find OEM #'s or good replacements..

Thanks
Keith

I can check with my dealer if no one has a parts for a 320, I have a 420 book and it does list two boom cylinder sizes do you know the bore and rod size of yours? cnt

Keith,

I have a 1957 Case Industrial wheel tractor with a 310 backhoe. Have the originial parts manuals for the 310 and 320 backhoe units.Cylinders are of the tie rod type and hydraulic boom cylinder, oem number 36070, seals at both ends of the cylinder. Rear seals ,packing type, case number: 30568 and wiper seal case no. 30574. seal for rear of cylinder is 49381 which is a seal o ring cylinder tube. packing piston: case no. 17578 and an A7623 seal o ring used with piston D23736 part numbers for the 320 backhoe unit. parts mostly identical on the 310 backhoe unit.

Keith if they are o-rings you may be getting the wrong hardness. O-rings are measured in a hardness rating of shore A durometer. If you have pieces of the original rings, take a piece with you to try and match the hardness. A good industrial seal vendor should have a device to measure the hardness. The material makes a difference too. Most times it would be Nitrile and you shouldn't be using anything less that 70 durometer. If you have 70 duro now, then try moving up to 90 duro Viton. They will cost you more but last longer.

OK, that said if you are not the original owner maybe the original seals were not o-rings and were somethinge else. O-rings are not the best technology for reciprocating seals. If they are piston seals and you have the piston out you may want to get 70 duro Tee seal sets. Tee seals are designed to use as reciprocating seals and the have back up rings to help close up the extrusion gap between the piston and the cylinder bore. You can convert to tee seals IF they were originally o-rings but this would mean taking the pistons to a machine shop and widening amd deepening the groove a bit. Stay with us here and the forum will help you solve your problem on way or the other.

Jim

I haven"t forgotten to respond to all your responses. Been busy and haven"t gotten back to the backhoe yet. Will probably be back on it this week-end.

Thanks for all the input and info..

Keith & Shawn(Gold Medal Winner)