1850D Tachometer Drive

Hi All,

I've got an 1850 w/o functioning tachourmeter. So far the cable is bad, but, I can't figure out what the other part is.

- Below the injection pump there is a right angle gear drive that slips over a gear that is protruding, and then the tach cable screws onto that. What is that right angle part? It spins freely when removed, but, the gear drive doesn't engage it. Teeth on the gear that is poking out are fine and spin when the engine is running; I'm assuming the teeth on the internal right angle thing are not so good and I need that part. I'm having trouble identifying it in the parts book.

Some googling indicates that this is a common fail with that internal drive being stripped out..and they are either hard to get or expensive or both. Can someone enlighten me?

Thanks,

J

I've never been able to find one. Mine stripped off, I pressed the shaft out and turned the gear around. That got a few more years out of it, but it stripped again. There's a long pin with kind of a key on one side that drives that unit. I've had those pins break too, so it wouldn't turn the gears. I think those are available if that's what's wrong.

Thanks rrlund; maybe these pics will help I assume the gear in the second photo is what you're talking about?

Is there any other fix? I assume the cable was damaged or something caused the drive not to spin and it chewed it all up..

I turned the worm gear around. If that driven gear is chewed, I'd turn that one too if you can.

The worm gear off the engine appears fine. The driven gear inside the 90 is what looks chowdered up on the edge that mates with the fixed gear. Oddly, they don't mesh very far together based on the amount of that gear that is gnawed up.

I looked at my 2-105, also with the Perkins. Same CAV pump and the same housing as the 1850, however, instead of there being a worm gear parallel to the block at the front with a 90deg drive, the tach on the 105 goes straight into the backside of the housing, facing the cab.

Is there another option to get a tach going that people have done; the gear inside the 90deg looks like it's had it's last... How do you properly get those caps off that 90deg? I knocked one out with a punch, but, it chipped off the lip (figured no big deal since the drive isn't sealed; I can fix that).

J

I think that's just a soft plug that's staked. I guess I did it the same way. About all you can do is put it back in and take a chisel or punch to bend the edge back over.

I had asked before about changing to the same drive that the 2-105 has. Somebody said I'd have to change that shaft that drives it.

The pin rrlund is talking about is very expensive from AGCO. I bought the pin from Reliable Industries, part # 6478641, for a very reasonable price. It just needs to be cut a little shorter to work. When I traded my 1850 last year I gave my spare 90 degree drive to the guy I traded to. I'm sure he still has it. Check with the Tractor Doctor in Mondovi, WI and see if it is still there.

FYI - The tach adapter part number is 158761A

Jake, when you say tach adapter, what are you talking about? I'd like to get mine going again too.

Thanks; I pried that cover off and filed the gear teeth to take the gnarled rolled over edges off and now it does drive.

any chance someone has the correct p/n for the diesel tach cable? I can find: 121695 or 122466 here on YT. I think the longer one, however, is the drive-side different on the Perkins tractors?

I believe the tach adaptor is what the 90* gearbox is called. At least that is what I called it when I bought my spare. The Tractor Doctor should still have my good spare and maybe they have another one as well. Look them up at tractor-dr.com. Very knowledgeable Oliver people. I got my spare from All States Ag Parts. They just happened to be pulling one off when I emailed them.

OK, thanks. I got a grill shroud for my 2-105 from the tractor doctor.

I think it'd be a different side and longer on the diesel. The gas would have driven off the distributor on the right side wouldn't it?

Thanks Jack!

rrlund: agree, I found 160221A after looking at the parts book, hard; it's 80 long for the inner cable.


Further digging reveals the part Jack indicated; it's actually a complete unit; the cover + gear + 90 adapter: 158761AV. Make sure you are sitting down.

158757AS is the shaft with core, 80 long for diesel FYI

Thanks Jack,

I figured that out, finally.. Went to local agco, discontinued and they can't get it. I found an auto one that is 81 long, I'm going to try that and see.

What is the block under the CAV pump that the tack plate and gear bolts to? I'm wanting to figure out an exploded diagram to see just what may be necessary to change this over to how the 2-105 is driven, given that the right angle drive is unobtanium. Mine appears to work now, but, I don't hold out long term hope .

J

I believe it's called the AUXILIARY DRIVE - DSL. 1850 Parts book page 16.

Change the quill shaft to one from a 2-105 or a Massey combine and drive it off of the auxillary shaft.

Thanks Jack,

Comparing to my 2-105, the aux-drive block appears different. At this point I think I have the right-angle adapter filed to where it will work. An 80 speedo cable is proper length, but, the driven end is the wrong configuration for whatever was meant to engage in the right-angle. Looking at it though, I'm positive I can fab something up that will allow it to engage. I don't know how long it might work given the poor shape that drive is in. When I stopped at the local agco they could find the cable core, but, it was no longer available.

The Aux drive on my 1850, as with others I've seen, has a large shaft with a key protruding from the back side--the side pointed at the operating position, exactly where there is some sort of drive for my 105. I suppose I could leave the original gauge in for show, but, stash a modern tach somewhere else just so I have it as this tractor will be doing work! I've been scouring the internet looking to see if any other perkins 6.354 used the same arrangement as the 1850 for tach drive; i don't think so. The closest thing I can find is this:

https://www.aetnaengineering.com/wp-content/uploads/2016/01/perkins.pdf

There are more annoying things to do next; previous owner appears to have panted the tractor, only with something other than Meadow Green, and, none of the dash and light components were painted white. That's driving me nuts!

J