Cummins 855 accessory drive

Bob

Well-known Member
Friend has a hay grinder with an 'ol Cummins 855 "Big Cam" and is having fuel pump drive coupling issues.

He NEEDS this machine today, and my 855 manual has wandered off.

Anyone have any info or comments on replacing the bushings in the accessory drive, and endplay specifications?

(This is a construction/industrial engine, and the "accessory drive" is subbed in for the air brake compressor.)

Thanks in advance for any help/comments.
 
I do not have a book that goes back that far here at work, I may have taken it home when I moved jobs to High Horsepower. Its been over 20 years since I have worked on one but think it has metal coupler. Ill try to see if I can open QuickServe on my laptop and maybe get a parts breakdown.
 
Thanks for your reply. I have a parts breakdown and parts list, but need overhaul info, ESPECIALLY the endplay specification.

Another guy worked on it, didn't think making sure endplay was correct, and it beat itself up again.

One guy suggested checking the crankshaft damper, which I hadn't though of, GOOD idea!

This machine is "new" to my friend, he ran it around 20 hours 'til it lost power, which was caused by the bolt in the accessory drive securing the front half of the fuelpump drive coupling breaking.

I wasn't around so he had "expert" look at it and put new bushings in the drive, 1.5 hours later it broke the front coupling half.

"Expert" told him it was the fuelpump, I said "no way" as the back half of the coupling will shear if the pump sticks, and it's MUCH lighter-made.

Pump shop went $$$ through pump, finding now problems, so now we have to figure out what's going on with the drive.
 
Hello bob,

There is a thrust washer that goes between the drive gear and the shaft. May be it was left out? never heard of a pump being the problem. it is not putting any high torque demand on the drive. That pump coupling would not last long! There is a bushing in the drive gear housing, is that the one that is bad? I can give you a break down of the parts for the drive as well as any other specs. I do know I have a manual for an 855, not that much different. I will look for it and let you know,

Guido.
 
I'll look for my book when I get my feeding done. The 855 is to old and too small for me to keep my books at work.
 
HELLO BOB,

My NH book has the specs as follow 0.002 to 0.012 for the NH. 0.004 t0 0.24 for the NTA. I would think that it can be that much different on the a big cam?

Guido.
 
(quoted from post at 12:53:49 12/11/18)
(This is a construction/industrial engine, and the "accessory drive" is subbed in for the air brake compressor.)

Not subbed in, they all have an accessary drive.
Haven't replaced a accessary drive on one of those engines since to late 90's but my 84 AM General has a 855 in it.
Loaned by manual out 10 years ago and it never came back.

Did they rebuild the drive or replace the bushing in the timing gear case and replace the drive?
Last ones I did I went to Cummins and got a replacement drive.
Damper won't cause the issue he's having.
 
(quoted from post at 12:53:49 12/11/18)
(This is a construction/industrial engine, and the "accessory drive" is subbed in for the air brake compressor.)

Not subbed in, they all have an accessary drive.
Haven't replaced a accessary drive on one of those engines since to late 90's but my 84 AM General has a 855 in it.
Loaned by manual out 10 years ago and it never came back.

Did they rebuild the drive or replace the bushing in the timing gear case and replace the drive?
Last ones I did I went to Cummins and got a replacement drive.
Damper won't cause the issue he's having.
 
Spent $12,500 on a inframe overhaul on a N-14 855 Cummins. Next week out on the road in NC the auxillary drive shaft broke. Another $2250 and came home and replaced the front dampner for another $1250. Hopefully after $16000 it should run for awhile...Oh, and a radiator...$1000 and a air to air cooler...$900...$17900.
 
Thanks to all who replied.

They still haven't retrieved the machine from the remote location it's at, so no progress, yet.
 
It has been many years since I replaced /rebuilt a Cummins accessory drive.But,as I recall,if you can move the pulley (using a pry bar) in and out more than a few thousandths,the thrust washer is gone.It will clunk when you move it if it is bad.But I am wondering if someone left the 'spider' out the goes between the fuel pump and the rear of the accessory drive.The spider is plastic star shaped piece that cushions the drive coupling. Mark.
 

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.

Back
Top