For example if your small pulley is 80mm diameter and spins at 1000 RPM and you need to find the second pulley. RPM Belt Length Speed Animated Diagrams. Movable Pulley Clipart Etc Pulley Block And Tackle Garage Storage Solutions (source : pinterest.com) Ad 4 to 48 Sheaves. Compound pulley . They are based on the work-energy principle. Humans use compound pulleys all the time. Ad 4 to 48 Sheaves. Drives provide economy and exceptional efficiency at speed ratios up to 7 to 1. Hi-Ratio Compound Pulleys for ¼ and ½ hp. If you know any 3 values Pulley sizes or RPM and need to calculate the 4th enter the 3 known values and hit Calculate to find the missing value. Pulley faces are made of highly durable plastic containing special additives to insure long service life. A compound pulley system will reduce the weight needed to move an object. Here is a physics based explanation of this type of simple machine. This system in its simplest form is described as a doub...