Hydraulic Elevator Calculator

This calculator sizes a hydraulic elevator's cylinder, pump, and motor from a force-balance and flow relationship, not a lookup table. Total force starts as (Car weight + Rated load) x gravity x a fixed 1.25 safety factor, then Roping multiplies that force (doubled for 2:1 roping) to get Cylinder Force (kN); Cylinder Bore (mm) follows directly as the diameter of a circle with area = force / Operating Pressure (MPa), so raising pressure across its full 1-25 MPa range always shrinks the required bore -- a higher-pressure system needs a physically smaller cylinder for the same load. That inverse relationship does not carry through to the pump side, though: Motor Power (HP) and (kW) come out completely unaffected by Operating Pressure across its entire declared range, because pump power is force x plunger speed (efficiency-adjusted) and the pressure term that shrinks the bore is exactly the pressure term that would otherwise appear in power -- the two cancel algebraically. Oil Flow Rate (L/min) and the derived Oil Tank Size (L), by contrast, DO fall as pressure rises, since a smaller bore moving at the same plunger speed displaces less oil per stroke.

Car Weight (kg) and Rated Load (kg) are what actually drive Motor Power, Oil Flow Rate, and Cylinder Force -- a heavier car or load raises all three regardless of pressure or roping. Roping (1=direct, 2=2:1) doubles Cylinder Force while halving Cylinder Stroke for a 2:1 system relative to direct-acting -- energy is conserved (force x distance is the same total work either way), so trading a shorter stroke for higher force is the entire reason roped hydraulic designs exist: a shorter ram avoids the long, buckling-prone single-stage plunger a direct-acting system would need for taller rises, at the cost of a stouter, higher-force cylinder. Motor Power itself is unchanged by Roping, because the doubled force and halved plunger speed cancel exactly (F x v stays constant).