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documentation page 1

Description of the the tag axle system. (3rd. axle) 1. General. The SBR 4000 is a vehicle with 3 axles. The 1st. axle is steered by the steering system as described before. The 2nd. axle is a rigid axle. The 3rd. axle is steered by roadforces at low vehicle speed. On this axle there is a pneumatic system which makes the axle rigid at high vehicle speed. 2. Make and type. The 3rd. axle is a ZF RL 75 A axle conform drawing 4474-675-028-ET001. On the axle tere are mounted two steeringdampers with a max. force of 3500 N. Furthermore there are mounted two pneumatic cylinders from the make Knorr conform drawing 2B72213. 3. Principle of the pneumatic cylinders. The house of the pneumatic cylinder is mounted on a support on the front side of the axlebeam. When the 3rd. axle at low vehicle speed has been steered in a right curve of the vehicle, and the right cylinder is acuated by air, the piston of the cylinder pushes the right steeringswivel into the straight forward position. The left steeringswivel follows this movement by the drag rod. The left cylinder has no function in this movement; the pistonrod of the left cylinder has only the function of a stopblock for the straight forward position (when the left cylinder has been actuated). In the same way the left cylinder, if actuated, pushes the left swivel into the straight forward position when the vehicle is in a left curve. Than the right cylinder has no function in the movement; the pistonrod has only the fuction of stopblock (when the right cylinder has been actuated). When both cylinders are actuated the 3rd. has the behaviour of a rigid axle, because the pistonrods of both cylinders have the function of stopblock for the swivels. 4. Pneumatic scheme. The pneumatic system for control of the pneumatic cylinders is given on scheme nr. 1152176/01. There are two circuits. The main circuit is circuit 4 of the four circuit safety valve. This circuit has been split up in two lines; one for the left and one for the right cylinder. In each of these lines there is an electric pneumatic valve. If these valves are not actuated electronically the air flows, via a double check valve, into the cylinders. The secundary circuit is circuit 3 of the four circuit valve. This is a backup circuit and operates (with only one line) in the same way. In both circuits there is a pressure switch with a setting of 5,8 bar between electronic pneumatic valve and double check valve to watch the systempressure. At least, for vehicles with a wheelbase (distance between 1 st. and 2nd. axle) less than 6.8 mtr there is a checkchoke between the cylinder and the double check valve.

Date: 2004.07.05

documentation page 2

5. Operation of the pneumatic system during vehicle use. The pneumatic cylinders are actuated automaticly conform the following matrix. situation main switch vehicle speed (± 2 km/h) [km/h] all speeds 0<v<10 0<v<10 0<v<10 displacement of steering wheel (± 30°) all positions. more than 100 degrees to the right more than 100 degrees to the left less than 100 degrees and less than 100 degrees to the right all positions all positions actuation of cylinder left side yes yes no no right side yes no yes no

1 2 3 4

off on on on

5 6

on on

7

on

8

on

10<v<25 25<v<30 after situation 5 25<v<30 after situation 8 v>30

no no

no no

all positions

yes

yes

all positions

yes

yes

Situation 2 and 3 is only controlled by circuit 4 and is a system option. On the dashboard there is a switch which makes it possible for the driver (e.g. on slippery roads) to actuate both cylinders in all the situations 2 untill 6.

Date: 2004.07.05

documentation page 3

6

Dashboard information-, warning- and error- system.

The dashboard has a matrix screen with three appearances of status. 1. information screen The normal status is as a matrix of information lamps. This is the situation when there are no warnings or errors. 2. warning screen When there is a warning a big yellow lamp lights on and during 5 seconds the matrix screen gives a warninglamp as definition of the warning. After these 5 seconds the matrix screen returns to the information status. The big yellow lamp stays as long as the warning exists. The driver can change the appearance of the matrix for a short look to check the warninglamp as definition of the warning. 3. error screen When there is an error a big red lamp lights on and the matrix screen gives continously an alarmlamp as definition of the error. The big red lamp stays as long as the error exists. The driver can change the appearance of the matrix for a short look in the information or warning appearance. In case of an error the driver has to stop as soon as possible. For the pneumatic system on the 3rd. axle there is one symbol for information, warning and error. The symbol is as shown below.

The information screen gives the symbol when the 3 rd axle is not rigid. (situation 2 untill 6 in the table above) The warning screen gives the symbol when one of the pneumatic circuits has no airpressure when it should have. The warning screen gives also the symbol when one of the sources of vehicle speed information (tacho or ABS) don't operate. When all vehicle speed information doesn't operate the 3 rd axle is rigid at all vehicle speeds. The error screen gives the symbol when there is for this system a relevant inacurate electrical connection. There is also the error screen in case of no pressure on both circuits, when there should be pressure. Date: 2004.07.05

documentation page 4

Parts list tag axle system; for pneumatic diagram see documentation page 11 pos no. 1 2 3 4 5 6 component description magnetic valve pressure switch check-choke valve two-way valve overflow valve piston cylinder supplier Wabco Wabco Serto Wabco Wabco Wabco VDL Bus no. 1153295 1192804 1153997 1153279 1153251 supplier no. 472 173 206 0 441 024 006 0 SO 47724-10-R1/4 434 208 054 0 434 100 133 0 2B72213

For complete pneumatic diagrams see documentation pages 11 and 12.

5

1

2

4

3

1

2

3

6

Date: 2004.07.05

documentation page 5 Diagram air susupension

Date: 2004.07.05

documentation page 6 Diagram air susupension

Date: 2004.07.05

documentation page 7 Brake diagram

Date: 2004.07.05

Information

7 pages

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