Bobcat 610 belt deflection?

Unicam · Jul 7, 2016

Ok, i'll try to keep this short, famous last words..... I just got a 610. It seems to need lots of love but does run and work after a fashion. I'd like to confirm it drives but am having trouble with my belt, it seems way too loose. I've been banging my head for 2 days now searching for an answer. It will try to drive but the belt slips and consequently the jackshaft/belt and machine stops. the variable sheave seems to "work" and it will drive when engaged, but if it isn't engaged the belt is way too loose. as soon as i try to move the levers, the belt and jackshaft stop. I've tried adjusting in on the 3 bolts on the driven sheave. the belt just seems to ride lower in it (?) and the belt stays loose on the drive clutch. (??) I wound up turning in those three bolts all the way, still the same slipping. ( and it won't open like that). I degreased the belt and it's within spec widthwise. Is there a way to add or remove a shim from the drive clutch to narrow up the gap? any help is much appreciated.

Unicam · Jul 7, 2016

also, I'm reading to bump the variable sheave lever a little to prevent belt slipping. On my unit it's a spring loaded lever that has to be held on with a bungee cord. there is no way to adjust the variable sheave a little. it's either not on at all, or it's all the way. can someone clarify the operation of the lever? should it have detents or friction? thanks again

Tazza · Jul 7, 2016

Unicam said:
also, I'm reading to bump the variable sheave lever a little to prevent belt slipping. On my unit it's a spring loaded lever that has to be held on with a bungee cord. there is no way to adjust the variable sheave a little. it's either not on at all, or it's all the way. can someone clarify the operation of the lever? should it have detents or friction? thanks again

Hopefully 6bnorma will pop his nose in shortly, he is the local 610 expert.
I'm sure he and others will have you up an running soon.

alchemysa · Jul 7, 2016

Tazza said:
Hopefully 6bnorma will pop his nose in shortly, he is the local 610 expert.
I'm sure he and others will have you up an running soon.

You should be able to adjust the sheave width with the variable speed lever thats near near your left hip. You haven't mentioned it so it sounds like you have no such lever.

alchemysa · Jul 7, 2016

alchemysa said:
You should be able to adjust the sheave width with the variable speed lever thats near near your left hip. You haven't mentioned it so it sounds like you have no such lever.

I was typing my earlier post when your second post appeared.
So you do have a lever. Does it actually work? Is it causing the variable sheave to open and close?

alchemysa · Jul 8, 2016

alchemysa said:
I was typing my earlier post when your second post appeared.
So you do have a lever. Does it actually work? Is it causing the variable sheave to open and close?

"" Does it actually work? Is it causing the variable sheave to open and close?"" To clarify... I meant the variable speed driven sheave thats attached to the engine.

Unicam · Jul 8, 2016

alchemysa said:
"" Does it actually work? Is it causing the variable sheave to open and close?"" To clarify... I meant the variable speed driven sheave thats attached to the engine.

Hello, it has the lever and when the lever is pulled the clutch closes. But the lever has no detents and its all or nothing and it bogs the engine down too much when all the way on. Basically for ease of explanation if I just start the machine, let it warm up, rev it up, push the levers and the belt stops. It's quite loose, I can turn it in the sheave just by pulling it.

Unicam · Jul 8, 2016

Unicam said:
Hello, it has the lever and when the lever is pulled the clutch closes. But the lever has no detents and its all or nothing and it bogs the engine down too much when all the way on. Basically for ease of explanation if I just start the machine, let it warm up, rev it up, push the levers and the belt stops. It's quite loose, I can turn it in the sheave just by pulling it.

The belt looks relatively new and measures 1 3/4 in width. The pulley sheave face looks good with no grooving. About the only thing left I can think of is the center to center distance if the clutches is too close. Maybe from oblinged engine mounts or something.

eboucher.6 · Jul 8, 2016

Unicam said:
The belt looks relatively new and measures 1 3/4 in width. The pulley sheave face looks good with no grooving. About the only thing left I can think of is the center to center distance if the clutches is too close. Maybe from oblinged engine mounts or something.

a new belt is 1 13/16 so you should be good on that aspect...

6brnorma · Jul 8, 2016

eboucher.6 said:
a new belt is 1 13/16 so you should be good on that aspect...

I have a number of questions before we can zero in on your issues. There are so many possibilities as to the root of the problem. Mounted on the engine is the "Variable speed sheave" not clutches……'clutches' are inside the machine. "Driven sheave/"jackshaft sheave" is the one with the spring and three pins. Variable speed valve is the one at your left hand. So……first, lets confirm it is in fact a M-610…….do you have a serial number? You can't imagine how many 610s I've seen advertised that in fact where a M-444 or M-500 and some of those machines used a different size belt. Second…..if I understand you correctly…..when you actuate the variable speed valve, the variable speed sheave in fact closes but when you release it the sheave opens again? Third….loosen those pins back up until something under 1/2 inch is exposed past the nuts. You have them "way" too tight. Pics would help.

6brnorma · Jul 8, 2016

6brnorma said:
I have a number of questions before we can zero in on your issues. There are so many possibilities as to the root of the problem. Mounted on the engine is the "Variable speed sheave" not clutches……'clutches' are inside the machine. "Driven sheave/"jackshaft sheave" is the one with the spring and three pins. Variable speed valve is the one at your left hand. So……first, lets confirm it is in fact a M-610…….do you have a serial number? You can't imagine how many 610s I've seen advertised that in fact where a M-444 or M-500 and some of those machines used a different size belt. Second…..if I understand you correctly…..when you actuate the variable speed valve, the variable speed sheave in fact closes but when you release it the sheave opens again? Third….loosen those pins back up until something under 1/2 inch is exposed past the nuts. You have them "way" too tight. Pics would help.

Also……you said the belt appeared to be almost new…..tell me what the part number is on the belt.

Unicam · Jul 8, 2016

6brnorma said:
Also……you said the belt appeared to be almost new…..tell me what the part number is on the belt.

thank you for the replys. I just walked in the door from work and need to head back out for kid errands. but I will get pics and info. Yes, that is the problem! As soon as i release the lever, the sheave opens back up! You know i'm a nube when i can't even describe my problem. I figured that was how it was supposed to be. I do have manuals and such but i'm having a hard time making sense of it all. I believe the valve matches the one in the book described as "variable speed valve with thermal relief". I'll try and snag some pictures. thanks again!

6brnorma · Jul 8, 2016

Unicam said:
thank you for the replys. I just walked in the door from work and need to head back out for kid errands. but I will get pics and info. Yes, that is the problem! As soon as i release the lever, the sheave opens back up! You know i'm a nube when i can't even describe my problem. I figured that was how it was supposed to be. I do have manuals and such but i'm having a hard time making sense of it all. I believe the valve matches the one in the book described as "variable speed valve with thermal relief". I'll try and snag some pictures. thanks again!

OK……..go to the "General Repairs" of this forum and look for the thread "M610 No/low turning speed" started by DannyTheVito……about half way through you will find discussion on valve repair/removal. Your valve is not functioning correctly for starters. I need the serial number of the machine and the part number from the belt to begin addressing the looseness issue.

Unicam · Jul 8, 2016

6brnorma said:
OK……..go to the "General Repairs" of this forum and look for the thread "M610 No/low turning speed" started by DannyTheVito……about half way through you will find discussion on valve repair/removal. Your valve is not functioning correctly for starters. I need the serial number of the machine and the part number from the belt to begin addressing the looseness issue.

I don't see an option to add pictures, maybe i need a few more posts to get that option? the id tag reads model 610, serial number 201792. the belt is a melroe 6515271 46-115 4407- 381. I read the topic, thank you. so for clarification would adjusting the allen or possibly putting a shim under it make the sheave stay closed? It does close right away and the machine seems to work fine if i hold the lever forward with a bungee cord.

6brnorma · Jul 8, 2016

Unicam said:
I don't see an option to add pictures, maybe i need a few more posts to get that option? the id tag reads model 610, serial number 201792. the belt is a melroe 6515271 46-115 4407- 381. I read the topic, thank you. so for clarification would adjusting the allen or possibly putting a shim under it make the sheave stay closed? It does close right away and the machine seems to work fine if i hold the lever forward with a bungee cord.

OK……that is a 1973 M-610 and that is the correct belt. First get the valve repaired and functioning and then address the belt issue.

Unicam · Jul 8, 2016

6brnorma said:
OK……that is a 1973 M-610 and that is the correct belt. First get the valve repaired and functioning and then address the belt issue.

Ok, so i should turn in the allen? sorry, I'm not exactly sure what needs to be done to the valve.

6brnorma · Jul 8, 2016

Unicam said:
Ok, so i should turn in the allen? sorry, I'm not exactly sure what needs to be done to the valve.

"IF" you are not leaking from the valve and "IF" you are not losing fluid from the variable speed sheave when you actuate the valve…..then yes, turn the plug in. However, from your description, I believe you would require a shim under the plug first….then replace the plug and tighten until the valve holds the sheave in high when actuated.
Don't forget to loosen those three pin bolts on your jackshaft sheave.

6brnorma · Jul 8, 2016

6brnorma said:
"IF" you are not leaking from the valve and "IF" you are not losing fluid from the variable speed sheave when you actuate the valve…..then yes, turn the plug in. However, from your description, I believe you would require a shim under the plug first….then replace the plug and tighten until the valve holds the sheave in high when actuated.
Don't forget to loosen those three pin bolts on your jackshaft sheave.

Sorry………"three pin nuts"

Unicam · Jul 8, 2016

6brnorma said:
Sorry………"three pin nuts"

ok thank you. in my haste, i turned the wrong one, the threaded nut one, compressing the spring on the other part, the one with the push-rod going thru it. i'm sorry i don't know the right names. I'm d-ripping with sweat grease and bug bites, I'll have to try it tomorrow after work. thank you for your help

Bobcat 610 belt deflection?

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