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Large cast iron v-belt pulley


Bought this 20+ years ago to build a hot air engine with. Never got around to it but now am curious what it actually came off of.

26" diameter with a 1" keyed hole with set screw.
Was told many years ago it was a rope pulley but the inside of the V part is smooth were most rope pulleys have teeth in them.


Bill Sherlock

Maybe it's the angle of the pulley in the picture but appears some spokes of the pulley are longer than the others??? That would mean the hole for the shaft wouldn't be in the center of the pulley.



eMail NOT Working
No, that very well may be a rope pulley.

IF it was smaller, and intended for hand-pull of a rope, then some sort of 'gripping teeth' might have been included, but if it was for machinery-drive, then it'd be smooth.

Rope-drive systems were common, and oftentimes, more popular in lineshaft drives of smaller circumstance than big power systems on belts.

A rope could be set up to run from room-to-room, turn in any direction, at any point, through most any radius, providing power to shafting to smaller tools, to run ventilation fans, and small lighting dynamos, much cheaper than leather belting.

Do a web-search for 'rope driven ceiling fan' for a cool example!


eMail NOT Working
BTW... you'll also find the smooth V is used in a 'round belt' application, but I don't think a wheel at this size would be.

The giveaway of the amount of 'power' transmission here, is the diameter of the keyed shaft... it's rather small. The fact that this is a large diameter sheave says two things.. .first, is that the shaft speed is low, and second, that there's lots of traction surface for a rope or belt... it didn't require much tension to transmit a fair amount of power.


I don't know about US usage, but V-belt drive was often referred to in the UK as a V-rope drive. The term is not much used these days though.



eMail NOT Working
Rope Drives have seemingly vanished from history, but they were once the king of large-facility power transmission. They could turn in any direction, and power all sorts of things. Where belts were limited to planes and angles and picky, manila and cotton rope went anywhere, and zipping along at 4500 feet per minute, carried tremendous amounts of power.


Page 121 of this document (marked page 108) starts the section on rope drives... and I have a couple other PDFs here that I found yesterday, all well-illustrating use of rope-based drives inside factories and mills.

Here's a neat writeup on OUTDOOR telodynamic transmission:


The obvious giveaway on a 'rope' drive system, vs, a V-belt, is the profile of the sheave groove... particularly, at the top. They're rounded, to prevent cutting the rope when it comes in at a slight off-angle.