Condition Reference value Reference
Emergency stop Disengaged Section 11 Common electrics, group 11.5.1.4
Emergency stop voltage (15E) Twistlocks Locked or unlocked, not intermediate position Twistlocks, description page 110 Overload
protec-tion
Boom up: passive
Boom down: passive or by-pass activated
Section 8 Control system, group 8.2.1 Overload protection.
Alignment Boom down: no alignment Maintenance manual DRF 400–450, section 7 Load handling, group 7.9.1 Twistlocks
D790-1 D794
7 Load handling – 7.2 Lifting/lowering 21
Pos Explanation Signal description Reference
1 Control lever (S815-P1) sends voltage signal proportional to lever move-ment to Control unit cab (D790-1).
Lower: US815-P1 = 0.5–2.0 V Zero position: US815-P1 = 2.0–
3.0 V
Lift: US815-P1 = 3.0–4.5 V 0.5 V is the highest lowering speed and 4.5 V is the highest lifting speed Lower voltage than 0.5 V and higher voltage than 4.5 V is used to detect de-fects in cable harnesses and controls.
Control lever, description page 7 Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.1 BOOM, menu 1
2 Control unit cab (D790-1) sends re-quest for Boom up or Boom down with speed information on CAN-bus.
Controlled by control system, error shown with error code.
Section 11 Common electrics, group 11.6 Communication
3 Control unit frame front (D797-F) acti-vates Servo valve, lift (Y6005) or Servo valve, lower (Y6004).
I = 380–650 mA Control valve lift lower and protrud-ing, description page 26
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.4 BOOM, menu 4 and 8.4.8.5 BOOM, menu 5 4 Control unit cab (D790-1) sends
re-quest for increased engine rpm on CAN-bus
Controlled by control system, error shown with error code.
Section 11 Common electrics, group 11.6 Communication
5 Control unit engine (D794) increases engine rpm.
Controlled by control system, error shown with error code.
-6 Servo valve, lift (Y6004) or Servo valve, lower (Y6005) pressurizes con-trol valve's lift spool with servo pres-sure.
- Control valve lift lower and
protrud-ing, description page 26
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.4 BOOM, menu 4 and 8.4.8.5 BOOM, menu 5 7 The control valve's lift spool changes
position and pressurizes valve block lift cylinder and sends load signal to the hydraulic oil pumps.
- Control valve lift lower and
protrud-ing, description page 26
8 The shuttle valve sends the strongest load signal if several functions are ac-tivated simultaneously.
- Section 10 Common hydraulics, group
10.5.3 Shuttle valve
9 The hydraulic oil pumps pump oil from the hydraulic oil tank.
See pressure plate on left frame beam.
Section 10 Common hydraulics, group 10.4 Pumps
10 The pressure reducer reduces the oil See pressure plate on left Pressure reducer, description page 24
22 7 Load handling – 7.2 Lifting/lowering
11 The accumulator stores servo sure. The non-return valve in the pres-sure reducer enables the prespres-sure to be stored when the engine is turned off.
See pressure plate on left frame beam.
Accumulator servo circuit, descrip-tion page 24
12 The servo filter cleans the servo oil before the control valve.
- Servo filter, description page 23
13 At boom down Control unit frame front (D797-F) activates Servo valve, blocking right (Y6001) and Servo valve, blocking left (Y6002).
U = 24 V Valve block lift cylinder, description page 27
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.2 BOOM, menu 2
14 For boom down, Servo valve, blocking right (Y6001) and Servo valve, block-ing left (Y6002) affect the blockblock-ing valves in the valve blocks for left and right lift cylinder, respectively.
- Valve block lift cylinder, description
page 27
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.2 BOOM, menu 2
15 For boom up, the blocking valves are opened in the valve blocks for left and right lift cylinder, respectively, by the hydraulic pressure from the control valve.
For boom down, the blocking valve opens and releases pressure from the lift cylinder.
- Valve block lift cylinder, description
page 27
16 The lift cylinders' piston side are pres-surized and the boom lifts.
- Lift cylinder, description page 31
17 Regeneration
Sensor hydraulic pressure lift cylinder piston side left (B768-12) sends volt-age signal proportional to oil pressure to Control unit frame front (D797-F).
NOTE
Regeneration is not possible near end-position or at overload protection.
Conn. 1: U = 5 V Conn. 2: U = 0 V Conn. 3: U = 0.5–4.5 V
Regeneration is activated when the pressure in the lift cylinders is 85 bar, regeneration is inter-rupted if the pressure reaches 185 bar.
Sensor hydraulic pressure lift cylin-der, description page 32
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.10.3 OP, menu 3
18 Control unit frame front (D797-F) acti-vates Solenoid valve regeneration right (Y6051) and Solenoid valve re-generation left (Y6052) if the pressure is sufficiently low for regeneration.
U = 24 V Valve block lift cylinder, description page 27
Diagnostic menu, see Maintenance manual DRF 400–450, section 8 Con-trol system, group 8.4.8.3 BOOM, menu 3
Pos Explanation Signal description Reference
7 Load handling – 7.2.1 Hydraulic oil pump 23
Hydraulic diagram A40740.0100
7.2.1 Hydraulic oil pump Hydraulic oil pump, general
See section 10 Common hydraulics, group 10.4.2 Axial piston pump with variable displacement.
7.2.2 Servo filter Servo filter, description
The servo filter protects the control valve's servo circuits against im-purities. The servo filter is located in the front edge of the lift beam on the right-hand side in the engine bay, between the pressure re-ducer and control valve lift, lower and protruding.
The servo filter is a low pressure filter with detachable filter car-tridge. The oil is cleaned when it passes through the filter cartridge filter material.
The filter cartridge is pressed against the upper section of the filter housing by a spring. Rubber gaskets seal between cartridge and fil-ter housing. If the back pressure through the filfil-ter is too great the cartridge is pressed down so that the oil passes through the car-tridge. This occurs if the oil is viscous (cold or incorrect viscosity) or if the filter cartridge is clogged.