Hi everyone, Thanks for the help in advance. I have a project with a piece of machinery that is rated to 105 HP @ 540 RPM. I was wondering what the torque rating for the machine would be, whilst its being driven from a diesel engine? I believe there is a direct relationship between Torque and Horspower from Engines; TORQUE = HP x 5252 ÷ RPM Therefore Torque = 105 HPx 2525 /540 RPM= 490.97 lb ft = 665.665938072 Nm 1) So I have done the math, but is that right? Is that really what the torque the machine can handle? I also have the torque and HP stats of the engine as below: I need to find the torque of the engine related by the rated torque capacity of the wood chipper = 665.7 Nm. @540 RPM? Also I need to find out what engine speed can provide the max torque rating for the machine as the engine has to be reduced by a ratio through pulleys to match the max RPM of the machine. My second question is: 2) Does reducing a gear ratio, say 3.7 : 1 multiply the torque by that much? So if; Torque x gear ratio = torque at the wheel Then @ 2000 RPM the engine would provide 169.1 Nm , therefore multiply by the 3.7037 times the motor is rotating faster than 540 RPM and you have the figure 625.92 which is under the figure we have for the rated capacity of the wood chipper. My third question is 3) Am I right? or is it all in my head? Thanks all . ..