jcb Robot 160 - High-Flow Circuit; Checking Flow and Pressure

Section E - Hydraulics
Fault Finding
High-flow Circuit
E - 47 E - 47
9803-9450-2
High-flow Circuit
In the event of poor attachment performance or hydraulic
overheating when using the High-flow circuit, the following
procedure should be followed to ensure optimum machine
and attachment performance.
Checking Flow and Pressure
1 Check the flow requirement of the attachment fitted
and compare it to the machine specification. Note that
the flow at the High-flow circuit is a combination of the
high flow pump and the auxiliary pump. If the
attachment flow rate requirement exceeds the total
machine flow then the attachment is unsuitable for
use.
2 Check the pressure requirement of the attachment. If
this exceeds the machine specification then the
attachment is unsuitable.
3 Only when attachment suitability has been confirmed
can the cause of the problem be established.
4 Check the flow and pressure setting of the High-flow
circuit as detailed below:
a Connect a flow meter, 400 bar (6000 lbf /in
2
)
pressure gauge and load valve between the high
flow couplings on the loader arm as shown K
Fig
37. ( T E-49).
b With the hydraulic oil at 50 °C (122 °F), the engine
at maximum speed and the load valve fully open,
operate the High-flow circuit and check that the
flow reading is as specified K
Table 10. Flow
Rates ( T E-47). Progressively close the load
valve and check the flow and pressure against the
figures in the table.
c If necessary, adjust the High-flow relief valve A so
that the correct specified pressure is achieved.
Table 10. Flow Rates
If poor attachment performance is still experienced after
resetting the High-flow valve and the flow rates and
pressure are correct, then the problem is with the
attachment. Consult the attachment service manual for
corrective action.
An example of a problem may be excessive back
pressure. No more than 12 bar (175 lbf /in
2
) should be seen
at the High-flow valve block. To check this insert a tee
piece and a 40 bar (600 lbf /in
2
) pressure gauge into the
return line at B. Check the pressure recorded by the gauge
with the attachment running.
Pressure L/min (UK gal/min) [US gal/min]
Max. flow, no
pressure
120 - 127 (26.4 - 27.9) [31.7 - 33.5]
100 bar (1450 lbf/
in
2
)
114 - 120 (25.1 - 26.4) [30.1 - 31.7]
120 bar (1740 lbf/
in
2
)
95 - 116 (20.8 - 25.5) [25.1 - 30.6]
160 bar (2320 lbf/
in
2
)
85 - 112 (18.7 - 24.6) [22.5 - 29.6]