Charge flow is a must on Series 40 models. When doing a closed circuit install it gives a positive pressure in the primary circuit to give flow for cooling and to help with leakage loss from the external valving or auxiliary system and to help flow and pressure for the control system. Your charge pump pressure needs to be the same all thru out working time so it want hurt the transmission. Series M23 doesn’t use a charge pump, but all the other series 40 models do.

There all of things that go into selecting a certain size, system pressure, speed, swashplate angle, type of fluid, temp, measurements of heat exchanger, size of hydraulic lines, control response and many many more. The charge flow needs these elements – sum of the charge flow needs of each of the parts in the system. Most of the time the charge pump displacement needs to be the same or greater of 10% of the total displacement of all units in the system. Most charge pump displacement is .85 cu. in.

Here are some reasons why it would not meat that 10% – low input speeds, shock loading, really long system lines, auxiliary flow needs and high torque low speed motors.

If you have any questions about charge pumps, need to replace yours, call us at 800-361-0068

sales@htsrepair.com