As the gears rotate around the motor housing, they carry
the oil that enters the inlet side of the motor to the outlet
side of the motor, where the oil is returned to tank.
This hydraulic motor is a fixed displacement, single speed
DETERMINING MOTOR EFFlClENCY
gear type motor. The construction of the winch motor is
shown in Figure 5K-1.
The rate of tail drain leakage, from a stalled motor, is a
measure of the motor's volumetric efficiency. A new
Port connections are located in the motor body. The direc-
motor, having maximum practical volumetric efficiency,
tion of oil flow through these ports determines the direc-
will have a tail drain leakage rate of approximately 4 GPM
tion of shaft rotation.
(15.14 I/min). A drain rate of 9 GPM (33.9 I/min) repre-
sents a volumetric efficiency of approximately 80 percent.
Oil entering one of the ports subjects two gear teeth on the
This is the point at which consideration should be given to
inlet side of the motor to high pressure which tends to
replacing or repairing the motor. The final decision on
Figure 5K-1. Winch Motor (41Q6)