jcb JS300 Service Manual page 501

Engine Speed Sensing
When the load from the hydraulic pump is high the engine
may not have enough power to maintain the pre-set rpm.
The MECU monitors the actual engine rpm and if it falls to
Key
1 Pump solenoid power setting (machine power setting)
2 Engine rpm (machine power setting)
3 Point for pump power reduction start - engine speed drop start pre-set
4 Point for pump power reduction end - engine speed drop end pre-set
5 Reduced pump solenoid power setting pre-set
(1) MECU default value
mA
610
600
590
580
570
560
550
540
530
520
510
500
1900
Engine Stall Prevention
If the load from the hydraulic pump causes the engine to
get close to stalling, the MECU will override the applicable
power band map and reduce the output to the hydraulic
pump proportional solenoid valve.
This happens when the engine speed reduces to a pre-set
value and remains active until the engine reaches a pre-
set 'stall recovery' speed.
The default values are minimum 1200 rpm and stall
recovery 1400 rpm.
C-76
4
5
1980 2000
rpm
Fig 12.
9813/5100-1
Section C - Electrics
Engine and Power Control
Engine Throttle and Power Mode Control
a pre-set value the power output to the pump proportional
solenoid valve starts to reduce.
The graph shows an example of the control function.
1
3
2
2130 2150
600 mA
2150 rpm
- 20 rpm (1)
- 70 rpm (1)
- 15% (1)
2100
C128360
C-76