Toro 98957SL Rev B Sand Pro 2020 3020 5020 Service Manual

Hydraulic Flow Diagrams
Traction Forward
The traction circuit of the hydraulic system consists of a
hydrostat connected in a closed loop circuit to three or-
bital vane wheel motors. Hydraulic fluid losses are de-
signed to occur from case drain leakage of the traction
pump (P1) and bleed off from the right wheel motor (M1).
These losses are replenished by the charge pump (P2),
which is integral to the hydrostat.
The charge pump (P2) is a fixed displacement  gerotor
pump. It  is driven  directly  off the  traction pump.  The
pump replenishes the closed loop circuit with fluid from
the tank. The charge relief valve (R2) supplies sufficient
head so that charge pump flow is guided to the low pres-
sure side of the traction circuit through one of two check
valves. Pump flow in excess of replenishment require-
ments is relieved through the charge relief valve back to
the tank.
The engine drives traction pump (P1) directly through a
coupling. The traction pump is a variable displacement
piston pump. The traction pedal connects through a link-
age to the trunnion shaft and swash plate of the pump.
With the  engine running and  the traction pedal  in the
neutral position, P2 supplies  no flow to the wheel mo-
tors. When the traction pedal is pressed to the forward
position, the linkage from the pedal positions the swash
plate in the traction pump so oil flows out port B. Oil flow
out of port B goes to the wheel motors and turns  them
in the  forward direction. On  the SP 5020,  the oil flow
goes through the front motor first and then through the
left and right  rear wheel motors. Oil flowing  out of the
wheel motors returns to  port A of the hydrostat  and is
continuously pumped out of port B.
The right wheel motor bleeds off a small amount of hy-
draulic fluid for  cooling of the closed  loop circuit. This
bleed off happens in the forward direction only. The high
pressure side of the motor forces a shuttle spool to shift
against a spring.  The pressure drop across  the motor
causes a  small amount of fluid  to bleed off  through a
fixed orifice on the low pressure  side of the motor and
then through the shuttle spool. This bleed off returns to
the tank through the oil cooler.
The acceleration valves reduce the rate of change in ac-
celeration  (jerkiness)   when  hydrostat  output   is  in-
creased by  the action of  the operator. An  increase of
pressure on the output side of the hydrostat will by–pass
some pump flow to the low pressure side of the pump.
The valve on the high pressure side closes at a predeter-
mined rate  as pressure increases.  This gives  the hy-
drostat a smooth acceleration rate when the swashplate
is stroked rapidly.
The hydrostat uses a small amount of hydraulic fluid for
internal  lubrication. Fluid  is  designed  to leak  across
pump parts into the case drain. This leakage results in
the loss of hydraulic fluid from the closed loop circuit that
must be replenished.
Hydraulic System (Rev. A)
Page 4 – 8
Sand Pro 2020/3020/5020
Product Specification
CategoriesLawn Mower Manual, Sprinkler and Irrigation Manuals, Toro Sprinkler and Irrigation Manuals
Tags, ,
Download File
Please Enter the Security Characters Shown Below. Letters are Case Sensitive. Your download link will appear upon completing this step.
- 170 pages
Document TypeService Manual
LanguageEnglish
Product BrandToro. Customer Service Representatives are available by phone: Monday - Friday 7:30 a.m. to 9:00 p.m. (CDT) - Saturday 8:00 a.m. to 8:00 p.m. (CDT) - Sunday 10:00 a.m. to 8:00 p.m. (CDT)
Canada 1-888-225-4886 USA 1-888-384-9939, Lawn Mower
Document File TypePDF
Publishertoro.com
Wikipedia's PageToro Company
CopyrightAttribution Non-commercial
(0 votes, average: 0 out of 5)

Submit your review (optional)
(will not be displayed)
* Required Field

Leave a Reply

Your email address will not be published. Required fields are marked *

*
*
Website