Drive and Control Systems for Loaders
Drive and control systems for loaders As with the travel drives the efficiency, high performance and operator comfort of the service hydraulics is of equal importance.
Very high demands are placed on the drive technology of mobile loading machines with regard to efficiency and driver comfort.
As well as the conventional open center controls and load sensing systems with fixed or variable displacement pumps the LUDV control, which has been developed and patented by Rexroth Hydraulics, is being increasingly applied.
The Mannesmann Rexroth Group of companies, with its business sectors of Brueninghaus Hydromatik and Rexroth Hydraulics, supply complete drive and control systems that fully meet these requirements. For loaders in the power range of up to 60 kW purely hydrostatic drives are the norm.
Advantages of hydrostatic drive systems
For the higher power range (> 60 kW) as well as the hydrostatic drives with a subsequent power shift gearbox, multiple motor drives with a summation gearbox are also utilised.
Optimum ergonomic Functional operation
Comfort
Low mechanical forces
With multiple motor drives two hydraulic motors operate in parallel and are connected to the drive shaft via a mechanical summation gearbox.
Optimum power utilisation Optimum machine utilisation
For the power range above 125 kW multi-motor concepts with switchable summation gearboxes provide the ideal solution.
Efficiency
High availability Reduced fuel consumption
The management of the entire drive train is controlled via a microcontroller.
Reduced exhaust emissions
Environment protection
Reduced noise emissions Standardised components Modular design Reduction of mechanical components
2
Operational safety
3
An overview of travel drive systems
6
30
5 25 4 3
20
2 15 1 0,5 10
5
Hydrostatic transmission
30
60
90
120
180
210
Drive power (kW)
with summation gearbox k 2 motors
with mechanical dircet through drive with summation gearbox k 2 motors k 1 coupling with summation gearbox k 2 motors k 3 couplings
K1 K 2 K 3 K 4
150
with power shift gearbox
4
250
Bucket volume (m3)
Unladen weight of unit (t)
Correlation of drive systems to power range
Drive
Power range < 60 kW
Hydrostatic k Hydraulic conversion, stepless k Shift (hydraulic motor) shock-free k No interruption of tractive effort
A4VG + A6VM
Power range > 50 kW Hydrostatic + summation gearbox k Hydraulic conversion, stepless k Shift (hydraulic motor) shock-free k No interruption of tractive effort
A4VG + 2 x A6VM + summation gearbox (without/with gear shift coupling)
Power range 50 – 100 kW Hydrostatic + mechanical k Hydraulic conversion, stepless + mechanical direct through drive k Shift virtually shock-free k Brief interruption of the tractive effort
A4VG + A6VM + summation gearbox (with gear shift clutch)
Power range > 60 kW Hydrostatic + power shift gearbox k Hydraulic conversion, stepless + mechanical switching stages k Shift (gearbox) virtually shock-free k Brief interruption of the tractive effort
A4VG + A6VM + power shift gearbox
5
Accelerator pedal
Inching pedal
Direction of travel
Tractive effort
Hydrostatic transmission
Override 1
2
Pump
Brakes Motor
Vehicle velocity
A4VG..DA Mechanical injection pump
A6VM..HA1R
Variable displacement pump A4VG...DA Data sheet RE 92003 Variable displacement pump A10VG...DA Data sheet RE 92750 Drive direction valve DA control valve for RPM related speed definition Load limitation control Integrated inching function, inching valve can be optionally controlled by the brake pressure Pressure cut-off
Variable displacement motor A6VM...HA1R Data sheet RE 91604 Load dependent control (HA1) Vg max circuit: Motor can be held in the Vg max position via a switching solenoid Valve for direction of travel signal sensing
6
Software Bodem Direction of Gear travel selection
Change manual/ automatic
Accelerator pedal
BB-3
1. Gear
Gear 1
Inching
RPM
Actual RPM
2. Gear Position actual value
Position command value
RS 232
Diagnostics Parameter setting Process monitoring
MC + Software LSG
Gear 2
BB-3
Tractive effort
Hydrostatic transmission with a power shift gearbox
Vehicle speed
K2
STM
Mechanical injection pump
Electrical actuator
A4VG..DA
A6VM..DA K1
Variable displacement motor A6VM...DA2 Data sheet RE 91604 RPM dependent speed selection Vg max circuit: Motor can be held in the Vg max position via a switching solenoid Valve for direction of travel signal sensing
Power shift gearbox with an A6VM Data sheet RE 91604
7
Accelerator pedal
Inching pedal
Direction of travel
Tractive effort
Hydrostatic transmission with summation gearbox
Override 1
2
A6VM..HA1U Brakes
Vehicle speed
A4VG..DA Mechanical injection pump
A6VM..HA1R
Software Bodem
BB-3
Gear selection
Direction of Accelerator Inching travel pedal pedal
MC + Software
BB-3
RS 232
Diagnostics Parameter setting Process monitoring
Tractive effort
Summation gearbox with/without coupling
A6VM1 x i1 A6VM2 x i3 A6VM1 /De-coupled A6VM2 x i3
Position actual value
Position command value
A6VM1 x i2 A6VM2 /De-coupled
RPM
A6VM1
Vehicle speed
K1 K2
STM
A4VG Mechanical injection pump
Electrical actuator
K3
A6VM2
Summation gearbox with 3 gear shift clutches
8
BB-3
Software Bodem Gear selection
Direction of Accelerator Inching travel pedal pedal
BB-3
RS 232
Diagnostics Parameter setting Process monitoring
MC + Software
Tractive effort
Hydrostatic transmission with a mechanical direct through drive
P nL
Switching point
K1 Mechanical direct drive
RPM
Position actual value
Position command value
Hydrostatic drive
Vehicle speed
Hydromechanical drive
A6VM
k Combines the advantages of the hydrostatic drive with that of the mechanical drive
STM
A4VG Mechanical injection pump
K2
Hydrostatic drive (working range)
Electrical actuator
k Maximum tractive effort at low diesel speeds
Hydromechanical drive
k High start-up efficiency k Jerk-free change of travel direction k Load limiting control also with power consumed by auxiliary actuators k Requirement dependent power distribution between the travel drive and service hydraulics
BKM
Hydrostatic Mechanical drive (changing the operating location) k Low efficiency losses k Reduced noise emissions
BKM
Mechanical
Hydromechanical drive - force transmission
9
Hydrostatic transmission for compact loaders
BKM
n1
n2
n1 = – n2
n1 < n2
n1 = n2
Steering via speed differences at the wheels on each side
4TH6
2 circuit drive with a compact tandem pump special design for compact loaders
MCR
4TH6
G2 G3 A10VG MCR
Tandem pump A10VG + A10VG
Boom
Bucket
Option
3 SM12
Wheel drive via MCR radial piston motor
Control of the implement hydraulics and the hydrostatic transmission via a joy-stick
10
11
Electronic control
Tractive effort Travel direction: limitation forwards/neutral/ reverse Accelerator Inching Constant pedal pedal Speed Drive
Software Bodem
BB-3
MC + Software FGR
BB-3
Variable displacement pump A4VG For closed circuit travel drives with electroproportional control. The pump for the implement hydraulics is fitted to the through drive (100% through drive torque).
RPM
Position command value
RS 232
Position actual value
Diagnostics Parameter setting Process monitoring
Data sheet RE 92003 Implement hydraulics
STM
A10VO/A11VO
A4VG Mechanical injection pump
A6VM
Electrical actuator
Variable displacement motor A6VM For closed circuit transmission with electroproportional control
Electronics for travel controls
Data sheet RE 91604
Variable displacement pump A10VO/A11VO For open circuit implement hydraulics controlled via a microcontroller Control block M7
Microcontroller
Data sheets RE 92701 (A10VO) and RE 92500 (A11VO)
Diesel motor
A4VG
A10VO/A11VO
Control block M7 Load sensing and LUDV – Anti-cavitation - pre-charge valve – Electrical float position – Separate tank line with regeneration Electronic control for implement hydraulics
Data sheet RE 64291 12
Electronic travel controls
Electronic implement hydraulics
k Direction of travel pre-selection k Pre-set speed k Acceleration/deceleration pre-selection k Drive characteristics – Working mode: flat characteristic curve – Travel mode: steep characteristic curve k Load limiting control k Inching/braking function k Over-speed safety for the engine k Hydraulic motor adjustment device – Electronic DA control – Vg max circuit
k Optimum levelling capability even due to the Z-kinematics k Load limitation, i.e. protection against over-loading the bucket k Weighting facility for the bucket contents k Diesel motor load limitation k Matching the working speed to the operator k Steering control via a joy-stick with a safety switch k Networking the diesel motor and travel hydraulics via a CAN-bus is possible (see below)
Microcontroller MC7 + Software FGR Encapsulated microcontroller for mobile applications Software with load limiting control for hydrostatic transmission with automotive speed control Data sheets RE 95050, RE 95057
Additional functions k Tractive effort limitation k Speed limitation – Crawl gear – Constant speed drive (CSD) k Fuel economizing driving k Integration of the service hydraulics
Electronic amplifier cards MHVA, MHVT Data sheets, RE 29875, RE 29880, RE 29882, RE 29883
Network via a CAN-bus Travel direction
Accelerator Inching Tractive pedal pedal effort
CSD
Diesel motor
Service Steering Variable Variable displacement displacement hydraulics pump motor
PC + Software Bodem BODEM
MC
MC + FGR
Service hydraulics
Travel controls
Control panel BB-3
BB-3
Diagnostics Parameter setting Process monitoring
Display Process monitoring (actual values)
CAN-Bus 13
6
30
5 25 4
Bucket volume (m3)
Unladen weight of unit (t)
Implement hydraulics for wheel loaders
3
20
2 15 1 0,5 10
5
30
60
90
120
150
180
210
250
Drive power (kW)
60 KW 80 KW 100 KW
Fixed displacement pump G2/G3
Variable displacement pump A10VO/3
For further information see data sheets RE 10030 and RE 10039
For further information see data sheet RE 92701
Steering
Boom
14
Bucket
Variable displacement pumps
Steering
Bucket
Boom
Fixed displacement pumps
Control block
Priority valve
Fixed or variable displacement pumps for the implement hydraulics can be mounted onto the through drive of (100% through drive torque) the variable displacement travel drive pump. A splitter box is not required.
Control block M1 and MO Open center control – Electrical float position – Regeneration valve Data sheets RE 64263 and RE 64266
Diesel motor
Drive with fixed displacement pump
Control block M7 Load sensing and LUDV – Electrical float position – Separate tank line with regeneration Data sheet RE 64291
Control block
Pilot control units 4THF6, 5THF6, 4TH6, 2TH6 – Electrical or mechanical detent – Float position function Data sheets RE 64522, 64553, 64555
Priority valve Diesel motor
Steering units LAGUV and LSPSD – Amplification and conversion for emergency operation – Priority valve Data sheet RE 14365
Drive with variable displacement pump
Cartridge valves and complete control blocks Data sheet RE 00182 15
Implement hydraulics for backhoe loaders Fixed displacement pumps G2/G3
Control block excavator
Additional equipment
Bucket
Hoist
Slew
For further information see data sheets RE 10030 and RE 10039
Support
Variable displacement pumps A10VO/3
Boom
For further information see data sheet RE 92701
Dipper Bucket
Loader control block with priority valve
Fixed or variable displacement pumps for the implement hydraulics can be mounted onto the through drive of (100% through drive torque) the variable displacement travel drive pump A splitter box is not required Control block M1 and MO Open center control – Electrical float position – Regeneration valve
Diesel motor
For further information see data sheets RE 64263 and RE 64266 Drive with variable displacement pump
For further information see data sheet RE 64291 Pilot control units 4THF6, 5THF6, 4TH6, 2TH6 – Electrical or mechanical detent – Float position function
Support
Additional equipment
Level compensation
Telescope
Boom/tilt
Service hydraulics for telescopic loaders
Control block M7 Load sensing and LUDV – Electrical float position – Separate tank line with regeneration
Loader control block with priority valve
For further information see data sheets RE 64522, RE 64553, RE 64555 Steering units LAGUV and LSPSD – Amplification and conversion for emergency operation – Priority valve For further information see data sheet RE 14365 Cartridge valves and complete control blocks
Diesel motor
For further information see data sheet RE 00182
Drive with variable displacement pump 16
Hydraulic remotely powered brake
Compact design k Piping reduced to a minimum k Parking brake electrically actuated k Possibility of directly mounting the accumulator
Brake light switch
Brake pedal
k Sensitive metering
2 circuit brake valve Accumulator pressure warning switch Accumulator loading valve
Parking brake valve
Additional (optional) actuators
Diesel
Diesel Spring loaded accumulator
Compact brake block LT13, Data sheet RE 66220 Accumulator loading valve LT06, Data sheet RE 66191
Compact brake block LT17, (for mounting in the drivers cab) Data sheet RE 66222
Modular design k Components have a low space requirement k Components can be located wherever required
Brake pedal
k Sensitive metering 2 circuit brake valve
k Quickly ready for operation
Brake light switch
Parking brake valve
Accumulator pressure warning Additional (optional) actuators
Accumulator loading valve
Diesel Spring loaded accumulator
17
1 circuit remotely powered brake valve LT05, Data sheet RE 66144
Inching brake valve LT31, Data sheet RE 66226
Steering Steering systems k Open centre steering with non reaction k Closed centre steering with non reaction (load sensing dynamic) Non reaction means that the occurring wheel forces do not act on the steering wheel via the steering hydraulics
EF
Service hydraulics
Priority valve P High pressure (not metered) High pressure (metered) Low pressure Suction pressure Entrapped oil Ambient pressure
LAG and LAS
Steering with chamber isolation - servo operation
RSM System The Rexroth stabilisation system RSM is built into the lift cylinders of the wheeled loaders and dampens out the pitching oscillations which occur whilst the vehicle is moving. The installation of the RSM system in wheel loaders result in the following further advantages: k Shorter braking distances k Stable steering characteristics k Higher transport speeds k Higher transfer rates k Greater comfort for driver k Lower repair costs or idle times 1 2 3 4 5
RSM valve Logic valve
LFA-D2 valve 4/2-way directional valve DBD valve (design tested) 6 Accumulator
Stabilisation module RSM For further information see data sheet RE 64615 18
Filtration
Criteria for the functional safety of axial piston units
Standard: suction filtration (A4VG / A10VG)
Filter rating To guarantee the functional safety of the axial piston units the following cleanliness classes are the minimum requirements necessary of the pressure fluids
B
k 9 to NAS 1638 k 6 to SAE k 18/15 to ISO/DIS 4406 For very high pressure fluid temperatures (90° C up to a maximum of 115°C) the following cleanliness classes are the minimum requirement
A
k 8 to NAS 1638 k 5 to SAE k 17/14 to ISO/DIS 4406
Variant: pressure filtration (A4VG / A10VG)
The finer the filtration the better the fluid cleanliness class obtained and the higher the service life of the axial piston units. Use filter without bypass. Recommendation: use clogging indicators.
B
A
Optimum cold start conditions for pressure filtration is achieved via the integrated filter short circuit valve
Variant: suction/return filtration B
A Return oil from the implement hydraulics
Advantages
k Low space requirements k Improved suction characteristics 19
Further information regarding filtration of the pressure fluids can be found in the pump data sheets.
Components Variable displacement pump A4VG Closed circuit Nominal pressure 400 bar Peak pressure 450 bar
Variable displacement pump A10VO Open circuit Nominal pressure 280 bar Peak pressure 350 bar
For further information see data sheet RE 92003
For further information see data sheet RE 92701
Variable displacement pump A11VO Open circuit Nominal pressure 350 bar Peak pressure 400 bar
Control block M7 Load sensing and LUDV For further information see data sheet RE 64291
For further information see data sheet RE 92500
Radial piston motor MCR Closed circuit Nominal pressure 400 bar Peak pressure 450 bar
Stabilisation module RSM For dampening the pitching movements which occur during operation
For further information see data sheets RE 15205 to 15210
For further information see data sheet RE 64615
Variable displacement motor A6VM Open and closed circuit Nominal pressure 400 bar Peak pressure 450 bar
Control blocks SM 12/18 RE 64122/124 SP 12/18 RE 64145/148 SX 18 RE 64127 M1-16/22/32 RE 64263 M7-22 RE 64287
For further information see data sheet RE 91604
Pilot control units 4/5THF6 RE 64553 4TH6 RE 64555 2-2TH6 RE 64552
Brueninghaus Hydromatik GmbH Glockeraustraße 2 D–89275 Elchingen, Germany Tel +49 (0) 7308 820 Fax +49 (0) 7308 7274
Mannesmann Rexroth AG Rexroth Hydraulics Jahnstraße 3-5 D–97816 Lohr am Main, Germany Tel +49 (0) 9352 180 Fax +49 (0) 9352 181040
RE 98056/04.98
Drive and Control
