This document provides an overview of the electric steering system used on BOMAG Variocontrol single drum rollers. It describes the key components of the electric steering circuit including the electric steering wheel, ESX control unit, steering valve, steering angle sensor and hydraulic steering circuit. The emergency steering valve is also described as an optional component that can only be operated via a special input code. Troubleshooting information and diagrams of the steering system are provided.

1. Service Training
12/2004
Teile-Nr. 008 099 94
Variocontrol
Single drum roller - 4
BW 177 / 213 / 226 BVC

2. Service Training
Variocontrol Single Drum Rollers Series 4
Table of contents
Foreword A 1
Documentation A 2
General B 1
Peculiarities B 3
Electric steering C 1
Steering circuit C 2
Steering pump C 4
Steering wheel C 5
Steering valve C 6
Steering angle sensor C12
Trouble shooting C15
Compaction measuring system D 1
BEM D 1
BTM plus D 2
BTM prof. D 3
BVC D 4
BVC - System E 1
Exciter system E 4
Gear pump E 5
Valve block E 7
Swashing motor E 9
Acceleration transducer E 10
MESX-control E 11
BOP E 12
Working principle of the system F 1

3. Service Training
Variocontrol Single Drum Rollers Series 4
Repair and adjustments G 1
Replacement of swashing motor G 2
Replacement of potentiometer G 3
Potentiometer adjustment G 4
Trouble shooting H 1
Electrics I 1
Service Training
MESX - Service Training
Wiring diagram
Hydraulic diagrams

4. Service Training
Variocontrol Single Drum Rollers Series 4 - A 1 -
Foreword
Reliable construction equipment is of greatest advantage for all parties involved:
• for the customer/user it is a basis for an exact calculation of utilization periods and the completion of
projects as scheduled.
• in the rental business it means that the equipment can be reliably used and planned without having
to stock a large number of stand-by machines.
• for the manufacturer it means that customers are satisfied, provides him with a good image and gives
him a feeling of confidence.
It is BOMAG’s philosophy to design and produce the machines with highest possible reliability. This
aspect of simple and easy maintenance was one of the key issues when developing and designing the
machine:
• the location of components in the machine eases maintenance work,
• the high quality standard of BOMAG is the basis for the considerable extension of the service and
maintenance intervals.
• the After Sales Service of BOMAG, including excellent operating and maintenance instruction
manuals, high quality training courses and on-site machine demonstrations helps the customer to
maintain their machines in good condition over a long period of time.
Permanent training of BOMAG’s own service personnel as well as the service personnel of BOMAG
Profit Centres and dealers is therefore a general prerequisite for BOMAG’s excellent world-wide service.
This program of permanent training is only possible with appropriate and up-to-date training material for
trainers as well as persons attending the training courses.
This training manual has not only been written as a support for the professional work of the trainer, but
also for the trainees attending these training courses.
The different levels of product training demand, that the training performed by BOMAG, its Profit Centres
or its dealers reflects the high quality of the training conducted at the Training Centre at BOMAG in
Boppard. For this reason we invested a lot of time in the preparation of these materials .
The structure of this training manual enables us to change or up-date individual chapters in case of
alterations to the machine.

5. Service Training
Variocontrol Single Drum Rollers Series 4 - A 2 -
Documentation
These Variocontrol training documents are valid for the following single drum rollers of series 4:
BW 177 DH-4 BVC
BW 213 DH-4 BVC
BW 213 DH-4 BVC + vibratory plates
BW 226 DH-4 BVC
For the BOMAG machines described in this training manual the following documentation is additionally
available:
Attention!
The currently valid part numbers for the documents can be taken from the Doclist or the
Customer Service page in the BOMAG (BOMAG Secured Area) in accordance with the serial
number of the machine.
1. Operating and maintenance instructions
2. Spare parts catalogue
3. Wiring diagram *
4. Hydraulic diagram *
5. Repair instructions
6. Service Information
* The document versions valid at the date of printing are part of this training manual.

6. Service Training
Variocontrol Single Drum Rollers Series 4 - B 1 -
General
BOMAG VARIOCONTROL (BVC)
The increased demands concerning quantity and quality in the application and compaction of soils and
rolled asphalt inevitably requires a permanent further development of vibratory rollers.
From the contractor's point of view a vibratory roller must fulfil three major requirements:
1. efficient operation
2. fulfilment of a task according to specification
3.flexible in use
Due to the inflexible parameterization, standard compaction systems are not able to adapt to the
permanently changing construction conditions in an optimal way.
However, this problem can be solved by the introduction of intelligent compaction systems. The control
values required for an automatic optimization of the compaction parameters are directly gained from the
interaction between drum and material to be compacted.
BOMAG VARIOCONTROL is a compaction system, which improves the quality and reproducibility of
compaction and enhances the efficiency of the roller, independently from the roller operator.
BOMAG VARIOCONTROL offers the user the following advantages:
1.Automatic adaptation of the emitted compaction energy to the actual compaction status
2. Better, reproducible results on all materials
3.No jump operation and therefore no particle destruction or loosening of material
4. The resulting direction of force is automatically adapted to the travel direction. This improves the
surface quality of the material and the gradability of the roller.
5.Low vibration loads for driver and environment
The further development of the VARIOCONTROL system for earthwork was founded on experiences
gained with the VARIOMATIC system used for asphalt compaction . The basic difference between
VARIOCONTROL and VARIOMATIC is the new exciter system.
It meets the demands of many users for an "intelligent" roller with automatic adaptation
of compaction.

7. Service Training
Variocontrol Single Drum Rollers Series 4 - B 2 -
Part of this new further development is the new display and control element BOP (Bomag
Operation Panel) in connection with the MESX.
Besides the display of the entire operation of the measuring technology the BOP also enables a simple
self diagnose of the overall system.
The operation of the BOP is described in detail in the operating and maintenance instructions.
Error and input codes can be found on the electrics page (MESX Service Training).
BOP ----- Bomag Operation Panel

8. Service Training
Variocontrol Single Drum Rollers Series 4 - B 3 -
Specialities
All BVC single drum rollers of series 4 are equipped with an electric steering
system as standard.
The hydraulic steering is also available as an option.

9. Service Training
Variocontrol Single Drum Rollers Series 4 - C 1 -
Electric steering
The electric steering consists of an electronically controlled closed control loop and a hydraulic steering
circuit.
The electronically controlled circuit consists of a small electric steering wheel (in the left hand seat
armrest), the ESX-control (located in the electric junction box), which converts the signal from the
steering wheel into electric signals for the proportional solenoids of the steering valve and the
steering angle sensor (located on the articulated joint), which feeds the steering angle back to the
control.
The hydraulic steering circuit consists of steering pump, high pressure filter, steering valve and
steering cylinders.

10. Service Training
Variocontrol Single Drum Rollers Series 4 - C 4 -
Emergency steering:
The emergency steering valve is only an option and can only be operated via a special
input code. The valve is supplied by the additional Variocontrol gear pump.
Pos. Designation Pos. in wiring diagram Pos. in hydraulic
diagram
Measuring values
05 one steering cylinder on BW 177 05
05 two steering cylinders
on BW 213 and 226
05
06 Steering valve with 2 proportional
solenoids and an integrated
accumulator
Y92 / Y93
Page 006
06
07 High pressure filter 12µm 07
09 Steering pump and charge pump 09 / MB 200 +/-10 bar
17 additional gear pump 5.5 cm³ on
BW 177 BVC
17 / MG 80 bar
17 additional gear pump 8 cm³ on BW
213 and 226 BVC
17 / MG 120 bar
20 High pressure line filter for
Variocontrol 100 µm
20
21 Optional emergency steering valve
with 2 B/W solenoids
Y112 / Y113
Page 006
21

11. Service Training
Variocontrol Single Drum Rollers Series 4 - C 5 -
Steering pump with filter
Steering pressure
Steering pump
Pressure test port
12 µm with
Steering circuit
High pressure filter
Pressure differential switc
3,5 bar
Filter outlet
Filter inlet

12. Service Training
Variocontrol Single Drum Rollers Series 4 - C 6 -
Steering wheel
The small steering wheel is located in the left hand armrest of the driver's seat
Pos. Designation Pos. in wiring diagram Pos. in hydraulic
diagram
Measuring values
Electric steering wheel A 45
Page 006
VCC 8,5 V

13. Service Training
Variocontrol Single Drum Rollers Series 4 - C 7 -
Steering valve, electrically proportional
The steering valve, together with the optional emergency steering valve, is located
behind a protection box on the right hand side of the frame under the operator's stand
or the cabin.
to the
Steerin
cylinder
from the
to the charge
system
pump

14. Service Training
Variocontrol Single Drum Rollers Series 4 - C 8 -
Steering valve
Pos. Designation Pos. in wiring diagram Pos. in hydraulic
diagram
Measuring values
1 Steering valve port P 06
2 Steering valve port T 06
3 Steering valve ports A and B 06
4 Steering valve, pressure relief valve 06 175 + 25 bar
5 Steering valve, shock valves 06 230 bar
6 Steering valve, accumulator 06 Accumulator
pressure 50bar
7 Steering valve, prop. solenoid Y 93 Page 006 0,4 - 1,2 A
8 Steering valve, prop. solenoid Y 92 Page 006 0,4 - 1,2 A
9 Emergency steering valve B/W
solenoid
Y 113 Page 006 0/12 V
10 Emergency steering valve B/W
solenoid
Y 112 Page 006 0/12 V
1 2
3
4
5
6
7 8

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16. Service Training
Variocontrol Single Drum Rollers Series 4 - C 9 -
Emergency steering valve (option, can only be operated via input code) !!!
9
10

17. Service Training
Variocontrol Single Drum Rollers Series 4 - C 10 -
BW 177 BVC
Pos. Designation Pos. in wiring diagram Pos. in hydraulic
diagram
Measuring values
1 Steering valve Y92 / Y93 06
2 Optional emergency steering valve Y112 / Y113 21
3 High pressure line filter 100µm in
Vario-circuit
20
1
2
3