Simple variable speed pulley idea.

[tigdlo]

Are you running a single or 3 phase motor?. A 3 phase motor runs smoother than even a resiliant mount single phase, adding moving parts with clearance to the drive train definitely isn't going to make that better.

I've read on other forums there is a noticable difference in chatter/resonance/parting ability by just changing from single to 3 phase even without a vfd, I haven't been able to compare this myself though.

 

[zx9]

@Reman having got back home and watched the video I linked to, I am not sure it would have been any help to you as it seems to be a different way of doing it, I don't really follow how the one in the video works.

 

[Reman]

@Reman having got back home and watched the video I linked to, I am not sure it would have been any help to you as it seems to be a different way of doing it, I don't really follow how the one in the video works.

Forgive me if this doesn't make any sense (I've got really bad back ache at the minute, and I've been self medicating with "Jack Daniels apple" since about 7pm..... I think I may have been over estimating the dose slightly though. ).

That system has a traveling spindle in the variable pulley (It can be raised and lowered). When that spindle is moved upward, it tightens the input and slackens the output belts. The tighter input belt pulls down further into the V, and pushes the centre part of the pulley across until it's against the side of the output belt and the forces on the centre section of the pulley is equalled out again. As the input belt is now riding much closer to the shaft, it's as if the pulley is now of a smaller diameter, and the reverse has happened with the output pulley.

On the face of it these look like a really simple system, But the width of the pulleys V, the angle the movable spindle travels in relation to the motor and machine pulleys, and the angles between the three shaft centrelines are all interconnected. If one's out than the system would slacken or tighten both belts while the speed was being adjusted. It wouldn't really be a hard setup to build, But only if all the dimensions and angles were worked out for me beforehand.

 

[Pete.]

All you have to do is get them more or less in line, and have the swing-bracket in the middle of it's adjustment when they are most in line. After that it takes care of itself.

 

[Agroshield]

The other advantage of the sliding centre version is that you get twice as much speed range (e.g. 50% to 200% of input speed) for a given lateral movement than with a single pulley. It is almost the same principle as a Kopp variator, which goes from 1/3 of input to 3 times input.

In the illustation below, the sliding pulley is in the centre, the driving motor is below and the driven spindle is above. Bonus nachos if you can identify the machine this is used on.