77
CHAPTER 5. HYDROSTATIC TRANSMISSION
4.9. PRECAUTIONS FOR INSTALLATION OF
HST UNIT
(1) INSTALLATION OF SHAFTS
a. The input shaft (output shaft) and the driving
shaft (driven shaft) of the two shaft type HST
should be aligned correctly. The deviation of
centering should be less than 0.05 mm.
b. When mounting or dismounting the two shaft
type HST onto or from the machine, prevent the
input and output shaft end from excessive thrust
load.
(2) INSTALLATION OF TRUNNION SHAFT
Provide a stopper in place before the maximum
inclination of the trunnion shaft when there is a
fear of application of stronger force to the trun-
nion shaft than HST operating force.
4.10. PRECAUTIONS AFTER INSTALLATION
OF HST UNIT
(1) STARTING
a. Fill the HST case with working fluid.
b. After the installation of the HST system, oper-
ate the control lever or pedal slowly several times
in order to bleed the system of air completely.
• When air-bleeding is incomplete, trapped air
bubbles make noise. Repeat the above air-bleed-
ing operation until such noise is elimiated.
• When excessive air is trapped inside the system,
the output shaft may not turn. But when the con-
trol lever is held at the maximum angle under
idling speed for a while, the shaft will begin turn-
ing. This may cause the machine to start abruptly,
so a safety measure should be provided such as
jacking up the drive wheels.
c. At first make sure there are no abnormal noises
or vibrations generated at low speed and then
acceralate to the specified speed.
(2) OIL TEMPERATURE
It is a very important factor at what temperature
a hydraulic system operates. High operating
temperaure will cause working oil to deteriorate
faster, that is, oil is oxidized faster. On the other
hand excessively low operating temperature in-
creases oil viscosity resulting in poor mechani-
cal efficiency of the HST.
Consequently abide by the following items:
a. When starting the machine at 10
°
C or colder tem-
perature, wait until oil temperature becomes
higher than 10
°
C by warm-up operation or us-
ing an oil heater. Then start operation.
b. Normal operating temperature: 20
°
C to 60
°
C
c. Maximum operating temperature
The maximum operating temperature should be
80
°
C. This limit is determined form the viscocity,
oxidation-proof property of working oil and de-
terioration of O-rings and oil seals. Consequently
operation at higher than 80
°
C will shorten the
service life of the HST and working oil.
(3) PERIODICAL INSPECTION AND CHANG-
ING INTERVALS OF WORKING OIL
As the system operates, deposits like sludge ac-
cumulate within circuits and oil tank and work-
ing oil deteriorates, which will prevent the sys-
tem from smooth operation in the end.
Consequently working oil should be checked
periodically to replace it timely with new one.
As it is very difficult to judge how oil has dete-
riorated visually, a rule of thumb is given below.
Normally the oil should be replaced after the
intial 50 hours of operaton and then every year
(before the new season begins) when the ma-
chine is used for less than 250 hours or every
250 hours of operation.
As water and sludge will be deposited in the cir-
cuits and oil tank when replacing the working
oil, the whole system should be flushed clean
before filling it with new oil.
Summary of Contents for SCM49
Page 1: ...S E R V I C E M A N U A L I S E K I L A W N M O W E R S LAWN MOWERS MOWER DECKS SCM48 SCM54 ...
Page 7: ...7 CHAPTER 1 INTRODUCTION 3 EXTERIOR VIEW AND DIMENSIONS 1935 mm 1965 mm 1100 mm 1265 mm ...
Page 36: ...36 SERVICE MANUAL FOR SGR19 SGR17 Fig 3 55 III 3 CYLINDER BLOCK 1 EXPLODED VIEWS ...
