ROLL PIN BREAKING

[low pressure guy]

Does anyone have any suggestions on why I keep breaking the roll pin on a TRANE CVHE vain main shaft to actuator arm. It happen every few months maybe. Pin seems to be tight in hole. I adjusted and checked stroke in and out manually on actuator at cams. Disconnected actuator and checked to see if vain linkage bines up and seemed ok . Machine runs well ,no surging.

[freonrick]

where are you getting the roll pin? the reason I ask is it may be too soft.

[referteacher]

What's the diameter of the pin. Is there enough meat on the actuator arm boss to drill it out another size larger?

Might not be a good idea on second thought. Maybe it's intended to be a "shear pin" in case something is binding.

I've seen the ball joints break, but never the roll pin shear off.

[r404a]

Low pressure,
Refteach is right; if you are using an OEM pin, I wouldn't neccessarily run out to get a hardened pin, so it will shear instead of something inside. Check real close to see if the control arm at the shaft has wallowed out. Is it first or third stage?


r404a

[greybeard]

that is not that an unusual problem.The roll pin does have to be a hardened pin also, either the first stage vane is sticking or out of adjustment to the point where it is driving or should I say over-driving closed. Disconnect the third stage and do an over-ride with the stepper motor to check both adjustment and to see if the vanes are binding. Generally what I have found is that the first stage vanes are rusty and that is what the root problem is

[chillrdude]

Over the years I have seen a bunch of third stage pins shear, after checking the vanes and linkages for any binding I would drill the hole out to the next size larger pin and never had any more problems.

[low pressure guy]

Guys its not the first or third stage vain arms its the actuator arm to the main shaft. I also disconnected linkage and checked to see if anything is binding and all looks good . I ordered new pins from TRANE. Last one were from graingers plain jane type.

[chillrdude]

This will probably get confusing but here goes, your saying it is the pin that links the vane actuator to the vane assembly crank arm ( this pin is usaully held in place with 2 cotter pins ), or is it the roll pin that links the crank arm to the assembly shaft. Either way I have never seen those pins break.

[grendil]

Check the shaft going over to the 1st stage Tang. Remove, clean lubricte. You will have to remove the pin to do this. Does the chiller have UCP or the new 5?

[chiller mekanik]

I've had the tang operator for the 1st stg vanes bend, I've had the pin on the ear that connects to the operator shear & I've had the ear break in half.

Each time this was due to the needle bearings on the vane assy binding up.

Has the machine been rebuilt lately?
Or maybe a leak on the suction elbow been repaired lately?
Often if the vane assy is exposed to the elements for a long period of time with out being sprayed really good with compressor oil, this will happen.

Replacing the needle bearings isn't a bad job once you get the assy on the floor.
You just need a comfortable milk crate, your favorite hammer, a punch kit & a piece of 3/4" black pipe about 8" long.
Mark everything, do one at a time, it should go pretty smooth.

I've never had any problems with the 3rd stg assy binding, I'm not saying it can't happen, it just hasn't to me.