Looking at a Cat 235B

[Daniel Davis]

I'm looking at a Cat 235B excavator for our farming operation. We run 2000+ irrigated acres and need an excavator from time to time. We could do with a 30K pound machine, but every now and then, an 80K pound machine would come in handy. That, and bigger older excavators seem to be cheaper than smaller older excavators.

Anyways, is there anything specific to look out for on a 235B? Any problem areas?

Also, I am looking at one that has a quick coupler - are there any other machines that would interchange buckets? 330 perhaps?

 

[Daniel Davis]

Anyone?

 

[Blocker in MS]

I cannot say anything special about a 235 other than the normal things....undercarriage, boom and stick pins and bushings, engine blow by, hydraulic pump strength....

 

[Manu]

A 235 is a workhorse that is a good reliable machine but is not as fuel efficient as modern hydraulic excavators. The engines are bullet proof , the pumps and hydraulic motors generally serviceable with pump servo seals easily changed when performance drops off. Swivel seals also eventually fail causing travel performance to wane. The swing gear box seal can fail causing oil to leak into the grease tray.The swing bearing can be worn if not greased properly.

 

[Daniel Davis]

A 235 is a workhorse that is a good reliable machine but is not as fuel efficient as modern hydraulic excavators. The engines are bullet proof , the pumps and hydraulic motors generally serviceable with pump servo seals easily changed when performance drops off. Swivel seals also eventually fail causing travel performance to wane. The swing gear box seal can fail causing oil to leak into the grease tray.The swing bearing can be worn if not greased properly.

That is all good to hear. Any way to tell the condition of the sing bearing?

Also, does anyone have specs or chrts of what it can lift at various distances?

 

[Manu]

To check the swing bearing set up a dial indicator with a magnetic base on the carbody close to the base of the bearing near the front of the cab and put vertical the pointer on the bottom edge of the bearing that is bolted to the upper structure.Have someone lift the bucket off the ground then zero the dial on the dial indicator.Then have the bucket lowered to the ground and apply sufficient down pressure to raise the carbody tracks slightly.Then check the reading on the dial indicator: anything less than .125" is acceptable. Then repeat the procedure every 45 degrees of rotation paying more attention to the side that the machine would dig from.

 

[Daniel Davis]

To check the swing bearing set up a dial indicator with a magnetic base on the carbody close to the base of the bearing near the front of the cab and put vertical the pointer on the bottom edge of the bearing that is bolted to the upper structure.Have someone lift the bucket off the ground then zero the dial on the dial indicator.Then have the bucket lowered to the ground and apply sufficient down pressure to raise the carbody tracks slightly.Then check the reading on the dial indicator: anything less than .125" is acceptable. Then repeat the procedure every 45 degrees of rotation paying more attention to the side that the machine would dig from.

Fantastic. We will definitely do this.

 

[Manu]

Keep in mind if that measurement indicates the bearings balls are worn it is possible to replace them. Of course that will necessitate undecking the machine and removing the bearing assembly. It is a messy challenging procedure but if time and suitable blocking or stands and jacking cylinders are available it is possible. A section of the outer ring has a plug that is held in with a tapered pin.The plug is large enough to allow the balls to be extracted. If all of them are removed the two races will separate.If the races are worn that bad it might be more feasible to install a good used one or a new one.It is possible to replace all the balls one at a time. The other consideration is the condition of the gear teeth on the inner
race.If there are missing or bad teeth then it should also add to the direction of that decision. That condition of the gear teeth can be assessed without undecking by removing a plug or cover which is for the purpose of checking and adding grease to that gear. It also is an indication of a problem when the feel of swing rotation is not smooth or sounds rough.