Talked to a rep at BLM today. They sell the clutch that is on my mill. I was trying to find out why I keep burning up pads and turns out the clutch on it isn't strong enough for the application. The horsepower rating is fine but it's the initial starting of all the wheels that is causing the problem, weight wise.
He also asked me what size belts I was using and how many. "B" and 2 of them. Turns out they are not heavy enough or I should have more. Did some surfing around and best I could find is that a B belt is rated for about 10HP each.
So, I should technically have at least 3 or even 4 belts driving my band wheels along with the next size clutch.
Something doesn't quite make sense here. I know the manufacturer cut corners but does it make sense that they would cut them this much? ???
Any input on what other 36 -42 HP sawmills have would be most helpful at this point. I was prepared to get a new clutch next time the pads needed replaced but I don't want to be replacing another driven pulley, which is already new, with one that has more grooves.
I am having some slipping problems on startup and wonder now if it is slipping while sawing causing problems. I thought I had all the bugs worked out and it is sawing much, much better now but maybe could still take some improving.
Any thoughts? :-/
That's interesting. I'll have to look again at the size of my clutch. It is bigger than the original that came on my mill but I've noticed some slipping again lately. I have three B belts on a 38 horse diesel. They pull, what I was told was, a 200 lb idle wheel and a 300 lb drive wheel. The weight of the wheels should help while cutting but I never gave the starting and stopping too much thought. I guess it is something to consider.
I'll tell you that two V-belts is not enough. When one of my belts stretches and the other two are pulling the load, I get slippage.
Neil,
The amount of power a Vee belt will transmit is based on the diameter of the smallest pulley. Are you using Bx belts, they will handle more power? I would not get too big (heavy duty) of a clutch. You are starting rotating of quite a bit of weight. If you get a (snap-action) clutch it is going to stress everything from the engine to belts to wheel bearings and the blade. If your band wheel diameter is approaching 30 inches, maybe you should let your saw blade run more and not stop it after every cut. I don't know how big of a job it is to replace pads, but you may have to figure its the cost of sawing like blades are.
Thanks Tom, I was afraid I was going to have to spend more money. :'(
Just can't figure why so many corners were cut. The guy at BLM was pretty much laughing and said it couldn't have been engineered too well to have so few belts pulling a large load. My wheels may be lighter than yours as they are only 24" and I believe your's are 26" or 28"? But with me changing the driven pulley to a smaller diameter to get the speed up, I may be changing the amount of torque being delivered. ???
Probably another reason for increased wear on the clutch.
Would like to hear how many WM uses on their LT70, but it seems like it may be standard on that size motor to go with 3 or more.
There is certainly room on the engine shaft and behind the pulley guard to go with a 3 groove but wonder if maybe I should measure for 4 if you get slippage on yours at 3.
May have to factor in as well, that I'm pulling 2" blades as opposed to the standard 1 1/4 or 1 1/2".
hey D, we were typing at the same time so didn't see your post.
As mentioned above, I have 24" wheels. I'm just using standard B's on mine. Had tried the one piece belt but had to change it back to 2 singles when I changed the pulley. As you mention, the snapping of the clutch is based on the springs in the clutch pak as I understand from the rep. A light spring would allow it to turn at idle and a heavy one allows the motor to get more up to speed before the clutch is fully engaged. Not sure what would work best. I thought maybe the lighter spring would work in this application but he didn't seem to think so.
I have quit starting and stopping it after the last pad change. Basically just leave it running until the log is cut. All the hydraulics work faster too so it pays off. I don't really want to have to factor that cost in as it's almost $100 every 100 hours plus the short time to change them out, which isn't difficult. I'd like to get a few more hours out of a set if I can.
I idle back when I take a break or quit. It's seldom that my clutch releases. The slippage I get is from sawing. It's unnerving when the band slows enough to lock itself in the cant. I think it is belt slippage in my case more than clutch slippage. I did melt the old one down though so I don't want to say it is all belt slippage.
When you put belts on your mill, make sure they are a matched set. The numbers on the outside will tell you if one followed the other in manuyfacture. It is difficult, if not impossible to tighten two or more belts that are not of the same length. Belts that are made at different times in the manufactureing process will be different sizes and composition just enough to cause trouble. The more belts you use, the more critical it becomes that they match.
Neil,
The Bx belt is 15hp for a 8 inch pulley. The price for the clutch pads seems high, could you have them rebuilt by a brake shop? Maybe a harder pad would last longer.
My drive pulley is 5" and the driven is 14". Not sure how much that would lower the rating. Even doing the math, I may be well off to go with the Bx and 3 belts giving me 45 HP to transfer over. Peak HP on my engine is 42.
I've checked my clutch and belts for heat after running to see if they were hot but doesn't seem to be. Course that's occasional, I don't check it all the time so still don't know if one or the other is actually slipping during sawing. It's the initial rev up that I can smell the rubber and imagine that's when the clutch slips as well.
I'll check around and see if I can find a shop to rebuild or maybe try BLM to see if they do have harder pads. Only thing is wouldn't harder pads have more tendency to slip?
BTW, D, everything is more expensive up here. ::)
Neil,
Is there any way you could reduce the acceleration of your engine from idle to full rpm.? If you smell burning rubber, its costing you money. I have seen some engine with speed dampeners, just a tube with a rod that has a disk on the end.
D, I'm not sure if I could do that or not. I would have to try and find a slow reacting actuator for the throttle I guess. Only thing is the longer it takes for the engine to get to full speed, engaging the clutch, the more the clutch would slip. No????
The actuator on it now goes from closed to open at the flick of a switch. Even with a variable switch installed, like those used on variable speed routers or something, not sure it would work for controlling the actuator. I had tried a spring from the actuator to throttle linkage back in the early summer but it didn't help. I remember now that it was smoking belts then too, that's why I tried the spring. So this really isn't a new thing due to me changing the pulleys after all.
Just the memory of the past summer I was trying to forget I guess. >:( ;D
Neil,
Does the actuator have linkage? If so, that is were a dampener is needed to reduce how fast it reacts. The dampener provides a load for the actuator. The dampener is doing the same thing as a shock absorber. You should have the clutch set to pull in at a lower rpm, this would reduce your slippage if you could bring the engine rpm up more slowly. A resistor in series with the actuator would reduce its pull and its speed, you could try this.
D, I'll try anything once ;). Problem is where would I get parts and how would I go about doing it? As far as I know too, is to get the clutch to engage earlier, I need a lighter spring on the pads. But the BLM rep told me it wouldn't disengage when idling. Still could try it anyway though.
Don't know a whole lot about this stuff but I'm learning as I go. 8) 8)
Neil,
What you need is a dampener something like a screen door closer, it prevent the door from slamming. Get one and take a look at it.
I'll see what I can find that is short enough. Only have about 4 -5 inches between the actuator and throttle linkage. Maybe a dampener off a small hatchback would work.
What about the resistor idea. Do you think a variable switch would work? I have no idea how a magnetic actuator would take to a lower voltage supply(?) but I suppose I could try one if I can find a 12 volt.
I wonder if BLM was getting at the idea that a bigger clutch would not engage until the engine was at a higher rpm. Heavier blocks = more inertia needed. ???
Hey Neil.
My Lt70 has 3 belts that are stuck together to make one bigbutt belt. I think they do this cause tightening the belt is the clutch. Simple as a rock but works well. ;D
Sometimes simple is the best thing going. Wish I could say the same :(. Another big diesel with 3 belts, why does mine only have two. >:( GEESH ::)
Only thing about the 'BX" "D" is talking about, is, they also require the "BX" pulleys. That is the type I have on my mill and I use 1 belt, not by choice ??? I pull the crap out of it and if it slips, it ain't much. Only time I stall the blade in the cut, is when it (used to) dive. Wonder why the "Powerband" won't work???. That is what Percy has ??? Takes a different pulley, also.???
There is bels and belts. All of them has a number and most manufactures has the same.
B-belt is an regular. Than You have SP-B that has a higher profile and take 1/3 more power but need wheels with deeper track. Perhaps You can read on the weel what type it is.
Some manufactures has a stronger, some calls it "red serie".
When You put new belts on a machine ALWAYS change all if there is more than one in parallel. A used belt NEWER pulls together whit a new.
Swede. (who have built diffrent machines since -85 but don´t speak english very much)
Don't worry Swede,we're a little rusty with our Svenske.