Q1. A screw jack with a 1-in. double-thread Acme screw is used to raise a load of 4000 N. A plain thrust collar of 50-mm mean diameter is used. Coefficients of running friction are estimated as 0.12 and 0.09 for f and fc, respectively. (a) Determine the screw pitch, lead, thread depth, mean pitch diameter, and helix angle. (b) Estimate the starting torque for raising and for lowering the load. (c) Estimate the efficiency of the jack when raising the load.

Q1. A screw jack with a 1-in. double-thread Acme screw is used to raise a load of 4000 N. A plain thrust collar of 50-mm mean diameter is used. Coefficients of running friction are estimated as 0.12 and 0.09 for f and fc, respectively. (a) Determine the screw pitch, lead, thread depth, mean pitch diameter, and helix angle. (b) Estimate the starting torque for raising and for lowering the load. (c) Estimate the efficiency of the jack when raising the load.