Trouble Shooting - Shibaura SX21 Workshop Manual

2. TROUBLE SHOOTING

CONDITION
Tractor fails to move when tractor
directional pedal is depressed
(HST output shaft does not rotate)
Tractor does not stop moving when
directional pedal is
(Output shaft fails to stop rotating
when directional pedal is released)
8 - HYDROSTATIC TRANSMISSION
POSSIBLE CAUSE
Parking brake is engaged
Improper HST linkage adjustment or
broken linkage
Damaged hydraulic pump
Charge pressure is low
High pressure relief/check
valve(s) malfunctioning
Charge pressure relief valve
malfunctioning
Air is mixing with hydraulic oil
Mechanical failure
Directional pedal linkage or HST
released linkage not adjusted properly or is
excessively dirty
High pressure relief/check
valve(s) malfunctioning
High pressure relief/check valve
seat(s) worn or damaged
Release parking brake
Inspect linkage adjust or repair as
necessary
Replace hydraulic pump
Test charge pressure circuit and
valve and repair or replace parts
as necessary
Check high pressure relief/check
valves and springs, replace as
necessary
Inspect charge pressure relief
valve and spring for proper
operation
Check hydraulic oil level and fluid
line connections for possible air
leakage
Inspect tractor drive train
Adjust linkage or clean as
necessary
Check high pressure relief/check
valves and springs, replace as
necessary
Inspect valve seats in port block
118
REMEDY