Fit of V belt pulleys on the shaft

[edison123]

I posted this in Mechanical Engineering Forum and received good tips about going in for taper lock pulleys.

Then, I remembered this Gear & Pulley Forum and thought this forum would give me more tips.

I received a 250 HP motor with some "noise" problem. On examination, I found that the noise was coming from the 8 groove, V belt pulley of the motor.

The motor shaft dia is 109.92 mm and the pulley bore is 110.20 mm i.e. 0.28 mm loose fit. The key was also loose both in the shaft and in the pulley.

The motor runs smoothly without the pulley.

I would appreciate if any one can point out the kind of fit of V belt pulleys (loose fit, mallet fit or interference fit) require.

Any pointers to web references would be nice.


I also have two questions.

1. The existing pulley is cast iron. Should I go for cast steel in case of taper lock ?

2. The existing straight bore pulley has 4 holes of 2 inches dia centrally in the thin stem area above the central hub. What is the purpose of these holes ?

(One theory is weight reduction, but given the total weight of the pulley, these holes on the thin stem do not save much in weight.)

Thanks in advance

 

[PeterCharles]

I would have used pulleys with taperlock bushes (or similar).

 

[diskullman]

Stay with the cast iron, unless you have too much moneyin your budget, in that case, still stay with the cast iron & make a donation to your favorite charity.
You may be able to re-use the existing pulley by reboring and using a power-lock bushing, also made by Fenner, or using adators made by Dodge, but it may be cheaper to just get a new cat iron pulley & taper-lock bushing new, as they are usually stock items.
You don't want a loose fit, and you certainly don't want to press a ulley onto the shaft, so one of the taper locking designs is perfect.
The holes are most likely to reduce weight.

Russell Giuliano

 

[edison123]

Thank you petercharles and diskhullman.

Reboring the pulley to suit a taper lock bushing is out since the central hub dia will not allow it.

I will go in for a new cast iron pulley with taper lock bushing.

 

[edison123]

One final question

I have a 1300 dollar quote for cast steel and a 1000 dollar quote for cast iron pulley.

Is spending additional 300 dollars for cast steel pulley worth it (in terms of better strength, less brittle, durability etc.) ?

Also, are the v-belts different for cast steel and cast iron pulleys ?

 

[edison123]

A feedback.

Motor fitted with cast iron, taperlock pulley. Working fine for the past 3 days.

I thank you all for your valuable tips.

*Nothing exists except atoms and empty space; everything else is just an opinion*