Variable Diameter Pulley for Transaxle Input

[Handy Don 12,235]

This is a variable-diameter pulley that @JPWH found and was willing to part with (big thank you!) to give me a hand on my 854 refurb.

 

I'm posting it in a separate topic because, frankly, it just so cool!

 

It is cast steel and nicely finished on all sides with one wall of the pulley fixed to the hub and the other wall threaded onto the hub.

A dogpoint set screw secures the fixed-side hub to the shaft. A separate dogpoint setscrew secures the threaded-side to one of the two flats on the threaded hub. 

 

The bore is ⅝" with a keyway which matches the input shaft on the 5060 and newer transmissions perfectly.

Outer diameter is 4" and and as you can see in the first image, with the movable side turned in tightly against the fixed side, it leaves a 4L belt about ⅛" proud of the pulley--effectively a 4.125" pulley. With the movable side turned away from the fixed side and flush with the outer end of the hub, The belt drops 0.5" lower into the groove, making it a 3.125" pulley. The threading range covers four full revolutions so the pulley diameter adjusts in eighths of an inch.

 

Factory for the 854 input pulley was a 4" but I'll initially set this for 3.5" to get a slight speedup (about 12%) since the 5060 being swapped in is a six speed. Ideally, I can get a compromise belt length that works well at that pulley diameter but still operates ok across its full range. The pulley adjusts with a simple hex wrench and the pulley doesn't have to come off the tractor to be adjusted as long as the belt has a bit of slack.

 

 

 

 

Edited March 25, 2022 by Handy Don

[953 nut 55,298]

   Years ago I outfitted packing house conveyor belts with those pullies so I could adjust the speed of the packing line to the number of people I had packing produce that day. Only took a couple of minutes and allowed more packers to work if needed without anyone standing around.

[ebinmaine 67,592]

10 hours ago, 953 nut said:

   

Agreed. 

 

The upper photo that shows the pulley at the larger setting jars my memory some. 

I've had one of those here that was on a very rusty tractor and unfortunately a broken pulley. 

I remember at the time wondering what the deal was. 

 

Cool stuff.  

 

 

[Horse Newbie 7,074]

If I saw one, and had never seen one before, I would probably think it was adjustable for different width belts, and the speed aspect/ changing the diameter of where the belt rides, would have flown right by me… until I adjusted it and the tractor took off like a rocket…

[ebinmaine 67,592]

1 minute ago, Horse Newbie said:

If I saw one, and had never seen one before, I would probably think it was adjustable for different width belts, and the speed aspect/ changing the diameter of where the belt rides, would have flown right by me… until I adjusted it and the tractor took off like a rocket…

 

 

Whheeeeeeeee

[squonk 41,150]

Find those  variable pitch pulleys all the time on rooftop exhaust fans. Guys would replace the belts and adjust those tight. Then later in the day I would get an alarm because a critical fan was overdriven and the overload was tripped!     

Edited March 25, 2022 by squonk

[Handy Don 12,235]

44 minutes ago, squonk said:

Find those  variable pitch pulleys all the time on rooftop exhaust fans. Guys would replace the belts and adjust those tight. Then later in the day I would get an alarm because a critical fan was overdriven and the overload was tripped!     

Sure, if this is on the motor side and was 3" then tightened up to 4" the driven pulley's speed goes up by a third.

[Pullstart 62,905]

Cool stuff!  Will you have enough adjustment in your clutch to allow speed changes at given times, or will you set the belt length according to your predetermined size?

[WHX?? 48,828]

I got a few of those and scrapped a ton more. Mostly 1/2 bore but might have been some 5/8 & 3/4

too. Back in the old days and even now on larger HVAC roof top units they were used for blower drives. Squonky knows.  Pretty much useless now in the days of direct drive for residential anyway. 

I didn't think they would stand up to horse duty. 

4 hours ago, squonk said:

Guys would replace the belts and adjust those tight.

Gotta get that air movin.... 

[Handy Don 12,235]

20 minutes ago, Pullstart said:

Cool stuff!  Will you have enough adjustment in your clutch to allow speed changes at given times, or will you set the belt length according to your predetermined size?

My plan is to size the belt for best operation at around the mid-point of adjustment -- 3½" diameter -- and then see how it does at the limits. A lot depends on the clutch pulley range to adapt without hitting the inside of the belt guard when engaged and being able to stop the belt when disengaged.

Standard belt is 70" with the 4" pulley. At 3" it should be a 68.5" belt. I'm gonna try a 69" and see how it goes across the adjustment range. I'll be sure to post what I find out!

Stock top speed is 5.5 mph. A 3" pulley is a 25% boost to a head-snapping 6.875!  

[Handy Don 12,235]

15 minutes ago, WHX?? said:

 

I didn't think they would stand up to horse duty. 

 

I have a small bit of trepidation on that, too. This is being spun at high speed and it's only an 8hp engine so, fingers crossed!

[WHX?? 48,828]

2 minutes ago, Handy Don said:

bit of trepidation on that

I've seen them walk or self adjust if the setscrew isn't super tight. Really messes up threads. Might be ok for  for a non worker small HP. 

[squonk 41,150]

1 hour ago, WHX?? said:

 

Gotta get that air movin.... 

Until it doesn't. The guys Pm'd the exhaust fans for the O'R's one evening. I get a call at 5:00AM from the OR charge nurse. All of the room alarms are going off an none of the automatic doors will close fully sealing off the sterile corridor. I knew exactly what was going on. Delayed operations about 3 hrs. until the sterile envelope was re-established and equipment was re-sterilzed. 

[Pullstart 62,905]

16 minutes ago, squonk said:

Until it doesn't.

Doesn’t a fan spinning too fast reduce the air movement at some point?  Is that what happened here?

[squonk 41,150]

14 minutes ago, Pullstart said:

Doesn’t a fan spinning too fast reduce the air movement at some point?  Is that what happened here?

Spinning the fan faster takes more energy. More energy means more heat in the motor. To much heat trips the motor overloads or the breaker.

 

Also too much air moving (before the motor trips can cause turbulence in the ductwork. In this case, an OR room is a positive pressure room and the air has to move in a certain way to create a sterile envelope around the OR table

[Pullstart 62,905]

8 minutes ago, squonk said:

Spinning the fan faster takes more energy. More energy means more heat in the motor. To much heat trips the motor overloads or the breaker.

 

Also too much air moving (before the motor trips can cause turbulence in the ductwork. In this case, an OR room is a positive pressure room and the air has to move in a certain way to create a sterile envelope around the OR table

Maybe I’m thinking of fans or blowers used for combustion.  I recall playing with a DC motor coupled with a venturi/gas valve assembly in a high efficiency water heater application and at a certain point, spinning it any faster kind of began missing the air instead of grabbing the air.

[squonk 41,150]

32 minutes ago, Pullstart said:

Maybe I’m thinking of fans or blowers used for combustion.  I recall playing with a DC motor coupled with a venturi/gas valve assembly in a high efficiency water heater application and at a certain point, spinning it any faster kind of began missing the air instead of grabbing the air.

Yes that can happen. The fan blades spin so fast the incoming air can fill in fast enough. Same thing happens with pumps. They have a curve and if you exceed it you end up lowering efficiency.

[Pullstart 62,905]

10 minutes ago, squonk said:

Yes that can happen. The fan blades spin so fast the incoming air can fill in fast enough. Same thing happens with pumps. They have a curve and if you exceed it you end up lowering efficiency.

see I’m not just full of hot air… I know most of what I tell people!  

[Maxwell-8 4,277]

Have been thinking about a MTD vario drive on a Wheel Horse

I think John Deere used a vario pulley for a while

[wallfish 17,011]

Hmmm, I like that pulley. Need to get me one of those to play with.

It appears to have a flat for the set screw instead of damaging the threads. Maybe drilling a dimple into that could help keep in place for the higher torque of an engine.

[Handy Don 12,235]

2 hours ago, wallfish said:

Hmmm, I like that pulley. Need to get me one of those to play with.

It appears to have a flat for the set screw instead of damaging the threads. Maybe drilling a dimple into that could help keep in place for the higher torque of an engine.

I'll get a shot of the flats when I'm in the shop next.

 

4 hours ago, Maxwell-8 said:

Have been thinking about a MTD vario drive on a Wheel Horse

I think John Deere used a vario pulley for a while

A number of GTs used them at different times. One of my Dad's Craftsman had it.

The mechanism had a splined shaft that the movable side slid on and something like a car clutch throwout to change the position.

[squonk 41,150]

    

[Lee1977 6,664]

On 3/25/2022 at 3:44 PM, Maxwell-8 said:

Have been thinking about a MTD vario drive on a Wheel Horse

I think John Deere used a vario pulley for a while

The JD's worked they had a hand control. The MTD's are junk.

[Lee1977 6,664]

I have a 6 double V variable for a 1 1/8" shaft weights around 15 lbs. Get that thing turning on a Kohler it would have torque like a diesel, make one hell of a mud tractor. 

 

 

[ebinmaine 67,592]

4 hours ago, Lee1977 said:

I have a 6 double V variable for a 1 1/8" shaft weights around 15 lbs. Get that thing turning on a Kohler it would have torque like a diesel, make one hell of a mud tractor. 

 

 

4 hours ago, Lee1977 said:

 

 

Lee, you get to thinkin' about selling that pulley ... Lemme know. That'd be great on a woods tractor too.