So I've been thinking. I have a hydraulic driven IR 40 CFM compressor on my truck. The compressor itself is belt driven. My question is, could you re size the pulleys to increase the CFM output of the unit. I can't see why it won't work, there is a temp cut out and a pressure cut out. So far as I see, the pump will either drive it or it won't. Doesn't seem to load up the motor in its standard gearing. A 25 percent increase would be nice and would more than cover for the loss taken by my desiccant drier. Opinions...?
Find out what the manufacturers max rpm for the pump is. Quite a few run at less rpm than they are capable of. I did try to gear up a compressor with a 16 HP Briggs twin by 25 percent, pump rpm was ok but it killed the engine before it unloaded. Back to the original pulley.
Hi Simonsrplant, Its a complex subject and you will have to provide a lot more detail for people to form an opinion for you. What are you using the air for, model of compressors and how it is unloading and so forth. I have done this many times for various reasons and very successfully. As RZucker said you need the specs on the compressor but also the manufacturer will provide graphs on there compressors that display shaft HP required at different head pressures and Rpm. Apart from the additional HP required you will have to review whether the pulley diameters and belts will transmit the additional load. You will need to guestomate what available HP you have from the Hyd motor also. The compressors work hard when run at max and will create more heat and usually lift a bit more oil if its a piston pump. If you were sandblasting for example the operating tank pressure will be much lower than the unload setting, so if you set your unloader just above that operating pressure you can adjust pulley Diam to extract every once out of your existing drive motor. I would not recommend doing this when using a electric drive motor by the way. Cheers