1
P Series
In some applications of the P Series Pumps, it is
desirable to move the machine for short distances at
low speeds without operating the engine. A screw-
type bypass valve is utilized in the pumps to permit
movement of the machine. The bypass valve is fully
opened when unscrewed two (2) turns maximum.
The bypass valve allows oil to be routed from one
side of the pump/motor circuit to the other, thus
allowing the motor to turn with minimal resistance.
An increase in resistance will occur with movement
at higher speeds. The bypass valve must be fully
closed during normal operation.
INTRODUCTION
The purpose of this manual is to provide informa-
tion useful in servicing the Hydro-Gear PC, PG,
PE PJ, PK, PR. PW and PY Pumps. This manual
includes the pump’s general descriptions, hydraulic
schematics, technical specifications, servicing and
troubleshooting procedures for the pumps.
The P Series Pumps normally will not require
servicing during the life of the vehicle in which it
is installed. Should other servicing be required,
the exterior of the pump will need to be thoroughly
cleaned before beginning most procedures.
GENERAL DESCRIPTION
The P Series Pumps can be combined with wheel
motors and other remotely located units. These
pumps provide an infinitely variable speed range
between zero and full displacement in both forward
and reverse modes of operation.
The P Series Pumps are of the axial piston design,
utilizing spherical nosed pistons. A compression
spring, located inside each piston, holds the nose
of the piston against a thrust bearing race.
The variable displacement pump features a cradle
swashplate with a direct-proportional displacement
control. Movement of the directional control shaft
produces a proportional swashplate movement and
a change in pump flow and/or direction.
Reversing the direction of the angle of the swash-
plate reverses the flow of oil from the pump and thus
reverses the direction of motor output rotation.
A fixed displacement gerotor charge pump is
provided in P Series Pumps. Oil from an external
reservoir and filter is pumped into the closed loop
by a charge pump. Fluid not required to replenish
the closed loop flows either into the pump housing
through a cooling orifice, or back to the charge pump
inlet through the charge pressure relief valve.
Check or shock valves are included in the pump end
cap to control the makeup oil flow for the system.
The size and type of check valve can play an im
-
portant role on the system pressure, response, and
amount of heat generated, due to the recirculation
of makeup oil flow. Shock valves are factory preset
pressure regulating check valves.
SECTION 1. DESCRIPTION AND OPERATION
Additionally, some pumps may be equipped with
an Auxiliary Pump. The Auxiliary incorporates the
principles of the charge gerotor assembly and pro-
vides the capability of an external auxiliary flow for
an alternate hydraulic circuit to operate accessories
without loss of drive.
WARNING
Actuating the bypass will result in the
loss of hydrostatic braking capacity.
The machine must be stationary, on a
level surface and in neutral when actuat-
ing the bypass.
Summary of Contents for HGM-H Series
Page 1: ...BLN 0043 January 2018 HGM H Series Motor Service and Repair Manual ...
Page 25: ...24 HGM H HGM H MOTOR EXPLODED VIEW ...
Page 29: ...HEMTM Series Motor Service and Repair Manual BLN 0083 January 2018 ...
Page 52: ...PRM MOTOR Service and Repair Manual ...
Page 56: ...PRM 3 EXTERNAL FEATURES PRM MOTOR Figure 1 PRM External Features ...
Page 77: ...24 PRM SECTION 8 PARTS LIST Figure 48 MA04K030 ...
Page 81: ...BLN 50231 January 2018 BDP 10L PL Hydrostatic Pump Service and Repair Manual ...
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Page 100: ...HGM 12P LSHT Wheel Motor Service and Repair Manual BLN 52197 January 2018 ...
Page 102: ...2 Exploded view HGM P ...
Page 117: ...HGM E LSHT Wheel Motor Service and Repair Manual BLN 52198 January 2018 ...
Page 144: ...2 P Series EXTERNAL FEATURES PC SERIES Figure 1 PC Pump with Standard Charge Pump ...
Page 146: ...4 P Series EXTERNAL FEATURES PJ SERIES Figure 3 PJ Pump with Standard Charge Pump ...
Page 147: ...5 P Series Figure 4 PK Pump With Standard Charge Pump EXTERNAL FEATURES PK SERIES ...
Page 176: ...34 PC Series Figure 16 PC Pump BOXES INDICATE ITEMS INCLUDED IN Kit Number ...
Page 192: ...52 PG PE Series Figure 17 PG PE Pump BOXES INDICATE ITEMS INCLUDED IN KITS Kit Number ...
Page 208: ...70 PJ Series Figure 17 PJ Pump BOXES INDICATE ITEMS INCLUDED IN Kit Number ...
Page 224: ...88 PK Series Figure 17 PK Pump BOXES INDICATE ITEMS INCLUDED IN Kit Number ...
Page 240: ...106 PR Series Figure 17 PR Pump BOXES INDICATE ITEMS INCLUDED IN KITS Kit Number ...
Page 261: ...HGM C LSHT Wheel Motor Service and Repair Manual BLN 52690 January 2018 ...