Title: OC-46 won't move and i'm confused
Post by: andy b. on September 26, 2004, 03:23:42 PM
Post by: andy b. on September 26, 2004, 03:23:42 PM
okay, i got the OC-46 running.
:D:D
now i am REALLY confused. when the crawler is in gear, it doesn't move (it sets there like it's in neutral). the suggestion was to put it in gear and pull back on one brake at a time. if you pull back on the left brake and nothing happens, and then you pull back on the right brake and the crawler starts moving, then i was told that meant that the problem was in the right final drive (most likely the small drive pinion). well when i put it in gear i can pull back on EITHER brake and it moves?!?!?!?!?! and if i pull back on BOTH brakes it still moves?!?!?!?! i pulled the rear tranny cover off, and it sure looks like the differential is working as it's supposed to. when the crawler is in gear but not moving anywhere the differential is moving and the differential gears are turning around. one note, when the crawler does move (when i pull back on the brakes) it drifts slightly to the left (i tried in first gear and reverse and it does the same thing). it is only very slightly to the left, and i don't know how straight a crawler is supposed to track.
any ideas????? i am confused by this and have no idea what to start pulling apart.
andy b.
:D:Dnow i am REALLY confused. when the crawler is in gear, it doesn't move (it sets there like it's in neutral). the suggestion was to put it in gear and pull back on one brake at a time. if you pull back on the left brake and nothing happens, and then you pull back on the right brake and the crawler starts moving, then i was told that meant that the problem was in the right final drive (most likely the small drive pinion). well when i put it in gear i can pull back on EITHER brake and it moves?!?!?!?!?! and if i pull back on BOTH brakes it still moves?!?!?!?! i pulled the rear tranny cover off, and it sure looks like the differential is working as it's supposed to. when the crawler is in gear but not moving anywhere the differential is moving and the differential gears are turning around. one note, when the crawler does move (when i pull back on the brakes) it drifts slightly to the left (i tried in first gear and reverse and it does the same thing). it is only very slightly to the left, and i don't know how straight a crawler is supposed to track.
any ideas????? i am confused by this and have no idea what to start pulling apart.
andy b.
Title:
Post by: mtncrawler on September 27, 2004, 04:58:33 AM
Post by: mtncrawler on September 27, 2004, 04:58:33 AM
The reason everyone is telling you to start the engine, put it in gear, let the clutch out and pull the steering brake levers one at a time is to determine which side of the final drive has gone bad. If one side has a broken axle, or if the drive pinion or bull gear have missing teeth, that side will freewheel and take all the power from the differential and the machine will not move. Kind of like an old Chevy with one of the rear wheels spinning on a patch of ice while the other sits on dry pavement. When you apply one brake on your tractor you are transfering that power back through the differential to the other side. That is why if the machine moves when the right brake is applied then the problem is in the right side final drive and vice-versa.
Title:
Post by: Blake Malkamaki on September 27, 2004, 06:13:47 AM
Post by: Blake Malkamaki on September 27, 2004, 06:13:47 AM
Don't jump at that conclusion too quickly. From what I recall it is just the oposite. For instance if you have one track on ice and the other on dirt and you are trying to pull something and the track on ice is just spinning and the tractor is not moving, pull the lever on the side that is not moving and it will tranfer power to that track. One's instict would be to pull the lever on the spinning track, but pulling the lever on the stationary track will transmit power to it. It's the way the power is transmitted through the controlled differential steering.
Therefore, it may not be the right side that is broken. More research is needed.
Blake
Therefore, it may not be the right side that is broken. More research is needed.
Blake
Title:
Post by: andy b. on September 27, 2004, 01:32:36 PM
Post by: andy b. on September 27, 2004, 01:32:36 PM
no, no, no. you guys missed the point.
the crawler engine does in fact now run. if i put it in gear it just sits there like it is in neutral. if i pull back on either brake lever, it starts moving. maybe i need a lesson on how to run an old Oliver crawler. do you have to pull back on the brake levers to start the crawler moving???? i have never driven a crawler before, so i have no idea what to expect.
andy b.
the crawler engine does in fact now run. if i put it in gear it just sits there like it is in neutral. if i pull back on either brake lever, it starts moving. maybe i need a lesson on how to run an old Oliver crawler. do you have to pull back on the brake levers to start the crawler moving???? i have never driven a crawler before, so i have no idea what to expect.
andy b.
Title:
Post by: andy b. on September 28, 2004, 12:20:55 AM
Post by: andy b. on September 28, 2004, 12:20:55 AM
okay, i pulled out the big guns and called Zimmerman's. those guys are great!!!!!:D
as Blake said, the way the differential works on these things is that if you start to apply one of the brakes, it kind of locks the differential and will divert power to the side you apply the brake to (yes, this seems wrong, but it is what happens). so what was happening with my crawler was that no matter which brake i applied, it started to lock the differential, and the "good" side would get power (the "bad" side also got power, but it is broken so it didn't help propel the crawler). Z-man told me to jam a cement block under the tracks one side at a time and pull on the brakes. he said that would provide resistance to forward motion to the bad track, and the good track would try to crawl over the block. sure enough, when i put the block in front of the left track, the right side would start driving and the crawler would turn to the left. when i put the block in front of the right track, i had to pull back all the way on the left brake (to basically lock it from receiving ANY power), and the right side drove right up over the block.
man i am psyched!!!! so i now know the problem is with the left drive. this weekend i'll pull the sprocket off and see if it is the drive pinion, drive shaft, or the bull gear (i hope the bull gear is okay). hopefully i'll have the machine back in action in two weeks or so!!!!!:D:D
once it's running i'll post a pic or two (although it is just your plain old OC-46).
andy b.
as Blake said, the way the differential works on these things is that if you start to apply one of the brakes, it kind of locks the differential and will divert power to the side you apply the brake to (yes, this seems wrong, but it is what happens). so what was happening with my crawler was that no matter which brake i applied, it started to lock the differential, and the "good" side would get power (the "bad" side also got power, but it is broken so it didn't help propel the crawler). Z-man told me to jam a cement block under the tracks one side at a time and pull on the brakes. he said that would provide resistance to forward motion to the bad track, and the good track would try to crawl over the block. sure enough, when i put the block in front of the left track, the right side would start driving and the crawler would turn to the left. when i put the block in front of the right track, i had to pull back all the way on the left brake (to basically lock it from receiving ANY power), and the right side drove right up over the block.
man i am psyched!!!! so i now know the problem is with the left drive. this weekend i'll pull the sprocket off and see if it is the drive pinion, drive shaft, or the bull gear (i hope the bull gear is okay). hopefully i'll have the machine back in action in two weeks or so!!!!!:D:D
once it's running i'll post a pic or two (although it is just your plain old OC-46).
andy b.
Title:
Post by: mtncrawler on September 29, 2004, 12:44:34 AM
Post by: mtncrawler on September 29, 2004, 12:44:34 AM
You guys really have me wondering now. I have broken two axles in Thiokol snowcats which use the same OC-4 steering differential as what's in Andy's crawler. First time we were able to get the machine out of the woods towing it with a chain and another cat. To point the broken machine in the right direction we would use forward and reverse gears holding the steering brake tightly on the snapped axle side only. Had to chain the cat to the second one to get it to turn - anchor the rear to use forward, anchor the front to use reverse - otherwise it would go pretty straight or follow the terrain downhill. After what seemed like a million direction corrections we had the machine out of there ( yes it was alot of work in a very long day and the next time it happened I had a towbar). Thing is, it wouldn't move at all without the brake on the bad axle side applied. I sure don't doubt you guys but what could have caused me to have such a different experience? More rolling resistance due to the wider tracks and being on snow? Is the lockup in the differential you are talking about very momentary, kinda like when you dump the clutch in the Chevy with the open rear end? The only repair that cat got was a replacement axle and it went back into service.
Title:
Post by: andy b. on September 29, 2004, 01:25:53 AM
Post by: andy b. on September 29, 2004, 01:25:53 AM
mtncrawler,
i would definitely say the difference between your situation and mine was the extra rolling resistance of the tracks. my OC-46 is in front of my garage on a flat paved surface, so as soon as the brake started grabbing and the diff locked, the crawler would just move forward because there was no resistance to try and make it turn. after seeing what happened with the cement block, i think if i would've pulled back hard on the left brake without the block, that the crawler would've turned left. like i mentioned, i am new to all this so i was afraid to get too crazy with the controls. when i put the block in front of the right track, i could feel the power gradually being applied to the right side as i pulled back harder and harder on the left brake. once i hit the point where the brake locked the left side, then the crawler jumped right up over the block. i'm sure people don't wish for a broken axle or drive pinion to see how their diff works, but i can say i learned something in the experience.:P
andy b.
i would definitely say the difference between your situation and mine was the extra rolling resistance of the tracks. my OC-46 is in front of my garage on a flat paved surface, so as soon as the brake started grabbing and the diff locked, the crawler would just move forward because there was no resistance to try and make it turn. after seeing what happened with the cement block, i think if i would've pulled back hard on the left brake without the block, that the crawler would've turned left. like i mentioned, i am new to all this so i was afraid to get too crazy with the controls. when i put the block in front of the right track, i could feel the power gradually being applied to the right side as i pulled back harder and harder on the left brake. once i hit the point where the brake locked the left side, then the crawler jumped right up over the block. i'm sure people don't wish for a broken axle or drive pinion to see how their diff works, but i can say i learned something in the experience.:P
andy b.
Title:
Post by: mtncrawler on September 29, 2004, 09:25:41 PM
Post by: mtncrawler on September 29, 2004, 09:25:41 PM
I'm curious about what you will find. Coincidentially my '55 OC-3 is is in the condition your OC-46 will be in - one track off and final drive opened up. Two broken teeth on the bull gear, although not next to each other so the machine still worked. The outer ring is replaceable if the rest is still good. The cage on my pinion gear bearing was warped out of shape and ready to fail so be sure and look there too. Good luck.
Title:
Post by: Blake Malkamaki on September 30, 2004, 03:45:10 PM
Post by: Blake Malkamaki on September 30, 2004, 03:45:10 PM
Guys, just to clear things up (or make it less clear...), the differentials in these crawlers (unless they have Spot Turn) do not "lock." One side speeds up in proportion to the other side slowing down, thereby maintaining continuous ground speed and control.