V-belt Power Transmission calculations.

[Iplayfarmer]

Is it reasonable to expect a single 1/2" v belt going around a 4.25" pulley to transmit 7 horsepower?

I modified my old Terratrac GT30 with a F140 continental engine to drive an aftermarket hydraulic pump with a v-belt. It runs great until I get a heavy load in the bucket. Then it squeaks. This is a crawler loader with a front end loader instead of just a blade. The belt slips somewhere between 500 and 1000 PSI. The loader still runs fine, albeit slower.

I calculated my 6 gpm pump running at 2000 psi would take 7 horsepower. Before I continue troubleshooting the existing system I figured I should ask if it's underdesigned. If the belt is just not capable of transmitting that much power, then I need to redesign rather than optimize this current system.

 

[the old grind]

I'd move up to a B belt or double the A size if sheaves have room and/or can be replaced.

A spring-loaded vs fixed tensioner may be of help with any configuration, esp if positioning can guide a belt around more of the smaller pulley.

 

[Texasmark]

Bely mfgrs. like Gates, publish that data in their belt catalogs, both the belt rating and the minimum shev diameter.

 

[Iplayfarmer]

I tried figuring it out through the Gates online stuff, but I ended up calling their engineering support number. I can't say enough good about their technician who answered the phone. It took all of about 90 seconds for him to tell me that my configuration was good for 4 horsepower, but that a Predator style belt could get me up to 9 hp. I have a predator belt on order from the local dealer, and I ordered one size larger of a pulley, too. The larger pulley not only gives me a better torque advantage, but it gives me more contact area with the belt. Both should increase the amount of horsepower I can deliver to the hydraulic pump. It will reduce the maximum gpm some, but I'm willing to give up a little flow to get the pressure up.