Content

Conversions:

1 hp = 42.4 Btu/min

=33,000 ft-lb/min

= 0.746 kW

1 gpm = 231 in. ³/min

1 psi = 6.875 kPa

1 bar = 14.5 psi

=100 kPa

=10⁵N/m­²

See Hydraulic Motor/Fluid Power Equations

Hydraulic Motor Equations:

Fluid HP = 5.83×10^-4Q∆P= Q∆P/1715

Mechanical HP = 1.585×10^-5TN=TN/63,025

Torque, lb-in = 36.8∆PDgal = ∆PD_in.3/2 π=0.159∆PD_in.³

Cost/Hour = KW × ($/kWH) = hp × 0.746 × ($/kWH)

Symbols:

D_gal = displ., gal/rev

D_in.³ ₌ displ., in.³/rev

Q= gmp

∆p= pressure drop, psi

T= torque, lb-in

N = speed, rpm

∆N= rpm change (const. accel)

∆t = time interval, sec

W = weight, lb_m

K = radius of gyration, in.

See Hydraulic Motor/Fluid Power Conversions

Fixed Displacement: Speed of rotation is proportionate to rate of fluid flow to the motor. Amount of fluid required to turn the shaft one complete rotation is always the same.

Rotary Actuating (Oscillating): Motor usually limited to a fixed degree of rotation. In some designs the motor turns a limited number of revolutions in one direction prior to reversal.

Variable Displacement: Motor speed and torque (twisting effort) output can be changed.

The Nutron BV Motor is uniquely a fixed displacement and variable torque hydraulic motor.

See Types of Hydraulic Motors

1. Determine load torque and speed
2. Pick motor type
3. Find displacement (motor catalog)
4. Calculate flow and pressure at each speed-torque point required; including stall, overspeed, braking, and creep.

Note: The pump provides constant pressure or flow to the valves that control the motor. Consider noise, efficiency, and fluids.