Copyright © Parallax Inc.
Propeller QUADROVER Robot (#28195)
v1.3 7/8/2008 Page 5 of 16
2.0 HYDRAULIC SYSTEM
2.1. Hydraulic System Overview
The QUADROVER’s 2.5 HP 4-stroke engine is coupled, through a clutch, to a hydraulic pump. The pump’s
output is split between two solenoid-actuated flow-cutoff valves to enable or disable flow to either the
left or right motor. The output of each of these valves is then connected through solenoid-actuated flow-
reverse valves to control the direction of wheel rotation. The hydraulic oil is then returned to the
hydraulic reservoir for reuse. The engine throttle is proportionally actuated by a Parallax standard servo.
Increasing the throttle and engine RPM creates increases flow and pressure through the hydraulic
system, resulting in higher speed.
Hydraulic oil pressure in the QUADROVER varies as the viscosity of the oil changes. Hot oil (above 165
°
F) could cause pump cavitations, excessive noise and wear to the motors. While the rating of the
hydraulic system is 2,800 PSI (continuous) and the pump is capable of developing pressure to 2,300 PSI,
this is generally not possible with the engine supplied in the QUADROVER. During tests, maximum
pressure achieved was between 900 to 1,000 PSI at 100 °F.
Temporary surge pressures up to 4,000 PSI are possible but unlikely. Surge pressures can be caused by a
forward movement which is quickly reversed without first braking and stopping the robot. Please follow
all precautions in section 5.3 and operating sequence instructions in section 5.4. Pressure also varies with
temperature. In cold weather oil viscosity is higher, causing more strain on the gas engine. Alternative
oils may be chosen for very cold or extremely hot climates.
2.2. Hydraulic Schematic
Motor
Left
Motor
Right
Pump
Flow
Valve L.
Flow
Valve R.
F. & R.
Valve L.
F. & R.
Valve R.
Reservo ir
470- 0004
470- 0003
470-0 001
470-0 002
47
0-
0
0
0
7
47
0-
0
0
08
47
0-
00
0
6
47
0-
00
05
4
70-
00
0
6
4
70-
00
05
* in
* out
* out
* in
3
3
1
1
4
4
2
2
2
2
1
1
Coil
Coil
Coil
Coil
in
o ut
Return
Return
o ut
* Norm ally -
Forwa rd
Rotation.
* Norm ally -
Forwa rd
Rotation.
High Pressure
Low Pressure
Low Pressure