TM 5-3805-260-24
When the bowl is empty, the time to fully open the
door and to move the ejector forward is approximately 7
seconds.
The time to fully close the door and to move the
ejector back is approximately ½/2 second less than the
time to eject forward.
If the travel time is not correct:
1. Check pump efficiency.
2. Check the setting of the relief valve for the bowl
and ejector circuits.
3. Check the operation of the ejector valve spool in
the control valve for the scraper.
4. Check the piston seals in the ejector and door
cylinders.
5. Check the door check valve.
Operating Speeds of the Elevator
Put a mark on one flight of the chain. Operate the
engine at high idle rpm. Use a stop watch to make a
record of the number of revolutions per minute.
OPERATING
SPEEDS OF
ELEVATOR
Speed
Chain
Seconds Per
Range
rpm
Chain Rev.
LOW
6.5 to 7
8 5 to 9 5
HIGH
10 to 11
5.3 to 5.8
If the operating speeds are not correct:
1. Check pump efficiency.
2. Check the setting of the relief valve for the
elevator circuit.
3. Check the operation of the control valve for the
elevator.
4. Check the operation of the elevator valve spool in
the control valve for the scraper.
5. Check the hydraulic motor.
6. Check adjustment of elevator chain.
CHECKING PUMP EFFICIENCY
For any pump test at a given rpm, the pump flow (gpm)
at 100 psi (7.0 kg/cm2) (690 kPa) will be larger than the
pump flow (gpm) at 1000 psi (70.0 kg/cm2) (6900 kPa).
The difference between the pump flow of two
operating pressures is the flow loss.
Method of finding flow loss...
Pump flow at 100 psi
57.5 gpm (litre/min)*
Pump flow at 1000 psi
-52.0 gpm (litre/min)*
Flow loss
5.5 gpm (litre/min)*
Flow loss when expressed as a percent of flow loss
is used as a measure of pump performance.
If the percent of flow' loss is more than 10% for test on
the machine or 15% for test on the bench, pump
performance is not good enough.
Example of finding percent of flow loss........
Percent
(gpm flow loss ) X 100 = of flow
(Pump flow @ 100 psi)
loss
(* 5.5) X 100 = 9.5%
or
(*57.5)
*Numbers in examples are for illustration and not
values for any specific pump or pump condition. See the
SPECIFICATIONS FOR 613B SCRAPER HYDRAULIC
SYSTEM for pump flow of a new pump at 100 psi and
1000 psi.
Test On The Machine
Install a 9S2000 Flow Meter. Run the engine at 2000
rpm. Measure the pump flow at 100 psi (7.0 kg/cm2)
(690 kPa) and at 1000 psi (70.0 kg/cm2) (6900 kPa).
Use these values in Formula I.
Formula I:
Percent
(gpm @ 100 psi - gpm @ 1000 psi) X 100
of flow
( gpm C 100 psi
)
loss
Test on the Bench
If the test bench can be run at 1000 psi and at full
pump rpm, find percent of flow loss using Formula I.
If the test bench can not be run at 1000 psi at full
pump rpm, run the pump shaft at 1000 rpm. Measure the
pump flow at 100 psi (7.0 kg/cm2) (690 kPa) and at 1000
psi (70.0 kg/cm2) (6900 kPa). Use these values in the
top part of Formula II. For the bottom part of the formula,
run the pump shaft at 2000 rpm. Measure the pump flow
at 100 psi.
Formula II:
Percent
(gpm @ 100 psi—gpm @ 1000 psi) X 100
of flow
(gpm @ 100 psi @ pump rpm
)
loss
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