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Bobcat 435 Drive Belt R&R

DGODGR

DGODGR

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Dec 18, 2009
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S/W CO
While performing some PM today I noticed that the drive belt looks as though it should be replaced. I'm not talking about the accessory drive belt (A/C, alternator)but they main drive belt that powers the hydraulic pumps. It is starting to show some cracks on the inside of the belt. I would like to know if anyone can comment on how to replace it. To me it appears as though all the hydraulic pumps would have to be removed as well as the exhuast system. If this is the case it seems like a pretty big job. I would think that Bobcat would have engineered things a little easier than that. We are talking about changing out a rubber belt here, not some major component.
As always, your help is appreciated.
 
willie59

willie59

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I haven't replaced the main belt on a 435. And Bobcat is one of those companies that doesn't have any info online. Is there any way you could post some pics of the arrangement? Most Bobcat machines that use a belt have some form of tension to loosen the belt for removal, but I don't know how the pumps are mounted and how that affects belt replacement. But I can say it's not unusual for Bobcat to make something that is a PITA to work on. :D
 
DGODGR

DGODGR

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Sorry no pictures yet. I have figured out how to do it though. It's a bit of a PITA but not as much work as I thought it would be. We have already got the old belt out but Bobcat sold me the wrong replacement. Hopefully we'll get the right part tomorrow so we can button her back up. I'll get some photos while it's apart so others can see it. Hopefully it will be of some help to somebody...someday.
 
B

bustedknuckle

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Apr 11, 2009
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Oakwood, Ga
Atco, it's somewhat like a loader drive belt, except the engine is on one side of the drive belt housing, and the pumps are on the other side.
 
Colorado Digger

Colorado Digger

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Dec 3, 2008
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Carbondale,co
??

:usalet me check on this thursday. i do remember some rumbling about this issue a while back. i will ask my mechanic what he has to comment on this deal.
i just remember some major going on's with a belt that required a lot of work.
regards, cd

:usa:usa
 
DGODGR

DGODGR

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Sorry, still no pictures. We started repacking wheel bearings on the A300 today (while we were waiting for the right belt to come in) and discovered some metal chunks in the Lft/Rr axle tube. I can't imagine why that would be. It appears (from the parts blow up, we have not gotten everything apart yet) that the only thing that could be bad is the bearing that rides next to the sproket. If it is that bearing I'm disappointed about the failure. Chain case oil has never been low, or contaminated, and it was changed at 1,999.5 hours (.5 hours before recommended service). No funny noises or vibrations. Big chunks of metal at the end of the axle tube though (flakes too). Anyway this little issue consumed all the spare time we had today. We had to work in the afternoon. I will have time tomorrow to work on the mini. We picked up the belt today so I should be able to complete the job in the morning.
 
DGODGR

DGODGR

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Finally

Here is the mini viewed at the engine door (open) with muffler and extra counter weight (if equiped) removed.IMG_0181.jpgIMG_0180.jpg
Only the rear section of the belt housing can be openned. The rear pump will stay attached to the housing. The length of the pump will only allow the housing to move a small amount.IMG_0185.jpg
All tension must be removed from the idler/adjuster pully so that the belt will have slack. It has a set bolt that needs to be loosened. Remove the belt from the front pully first. The inboard side of the belt housing, at the front section, is open. This allows the belt to be removed and replaced by slipping it over the pully towards the center of the machine. Then slip the belt through the gap between the rear pully and the pump gear. It's just enough of a gap to get the belt out, and in, if you twist it sideways so that the thinnest profile will slip between the pump drive gear and the rear pully. When assembled the pump gear slips inside the center of the rear pully.IMG_0182.jpg
The belt is a "powerband" type so each pully has several splines/groves that mate up with the inside of the belt. Be sure to put it on the front pully correctly. If not the belt will be too tight to get the tension indicator to line up correctly. The belt should be pulled over, the rear pully, top first (opposite what the photo shows). The belt is very tight, when new, and will require "bumping" the engine to get the belt over the back pully. Insert a 3/4" x 2.5" x 10UNC bolt and set the belt tension. This whole is on the bottom of the house (directly below the tensioning pully). The tensioner indicator is shwon here on this label (affixed to the machine in the door jam).IMG_0184.jpg
Be sure to tighten the set bolt for the idler pully. Remove the adjusting bolt (the 3/4" x 2.5" bolt). Replace the muffler and the extra counterweight (if equipped). Run the machine for a bit and recheck the belt tension (the indicator). Adjust as required.
 
DGODGR

DGODGR

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Finally

I believe the correct label for the required tensioning bolt is 3/4"-10UNC x 2.5". Sorry.
 
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