AR42.80-S-1603M | Remove/install rear axle ALB controller | 2.2.09 |
MODEL 638
except CODE (BB0) Antilock brake system (ABS)
except CODE (CL0) Rear air suspension, lowerable and liftable
S42.80-2517-09
1 Governor
2 Spring
3 Adjuster spring
4 Adjusting nut base
5 Adjusting nut
12 Screw
14 Screw
15 Actuating lever
6 Counternut
7 Actuation linkage
8 Guide sleeve
9 Lock washer
10 Control carrier plate
Modification notes
| Checking | ||
1 | Checking and adjusting load-sensing governor (1) of rear wheel brake | ||
2 | When brake pedal is depressed fully and firmly, inspect operating lever (15) of control for unobstructed clearance | Replace pressure regulator if necessary | |
3 | Check hydraulic exit pressure | If the pressure differential exceeds the maximum value, the pressure regulator should be replaced. Pressure regulators cannot be repaired and must be replaced in the event of function errors. | |
| Removing | ||
Danger! | Risk of death caused by vehicle slipping or toppling off of the lifting platform. | Align vehicle between pillars of lifting platform and position four support plates at lift mounting points specified by vehicle manufacturer. | |
4 | Raise vehicle | ||
| Special instructions for lifting and supporting vehicle | Model 638 | |
5 | Release parking brake brake cable from its suspension | ||
6 | Loosen jam nut (6) and adjusting nut (5) of adjuster spring (3) | ||
Danger! | Risk of poisoning caused by swallowing brake fluid. Risk of injury caused by brake fluid coming into contact with skin and eyes. | Only pour brake fluid into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid. | |
7 | Unscrew brake lines on control (1) | Place a suitable vessel under the control to collect brake fluid which runs out. Do not deform brake control lines in order to be able to perform the reinstallation free of tension. | |
| Brake fluid notes | All models | |
| Notes on repairs to brake system | All models | |
8 | Remove mounting bolts (12) of control (1) on carrier plate (10). Remove control. | ||
9 | Remove lock washers (9) on operating linkage (7) | ||
10 | Unhook adjuster spring (3) and detach guide sleeve (8) | ||
11 | Detach operating linkage (7) | In the event of difficulties when removing the operating linkage on account of a shortage of space, lower the semi-trailing arm. | |
| Clean | ||
12 | Clean all parts which have been removed | ||
| Checking | ||
13 | Check parts which have been removed for faultless condition | ||
| Install | ||
14 | Install operating linkage (7) on semi-trailing arm. Mount guide sleeve (8) and engage spring with adjustment screw (3). | To do this, insert lock washers (9). | |
15 | Engage spring with adjustment screw (3) on control (1) | ||
16 | Attach control (1) to carrier plate | | |
17 | Screw brake lines onto control (1) | ||
18 | Attach adjusting nut base (4), nut (5) and jam nut (6) on spring with adjustment screw (3) | Do not apply pressure to the brake pedal. | |
19 | Bleed brake system | ||
20 | Adjust control (1) of rear wheel brake ALB [axle load-dependent brake] | The rear axle geometry should be adjusted before regulating the rear brake brake pressure controller. | |
| Checking | ||
21 | Check all the connections of the brake line affected by the repair for leaks | ||
22 | Check pressure of brake fluid between the wheels | The pressure regulation of the rear wheels takes place via two independent brake circuits. All pressures going beyond the maximum values should be considered as a malfunction . | |
23 | Check pressure differential between the various diagonals of the brake circuit in the master brake cylinder | A pressure differential between the various diagonals of the circuit can occur due to spring tolerances between the primary and secondary circuits. All pressures going beyond the maximum values should be considered as a malfunction . |
Test values for ALB controller
Number | Designation | Model 638 | ||
BE42.80-N-1001-01B | ALB controller pressure test | Inlet pressure | bar | 120 |
Maximum variation of outlet pressure between left and right | bar | 4-6 | ||
BE42.80-N-1002-01B | Spring dimension "D" for rear axle load | <600 kg | mm | 641 |
601-650 kg | mm | 651 | ||
651-700 kg | mm | 671 | ||
701-750 kg | mm | 681 | ||
751-800 kg | mm | 701 | ||
801-900 kg | mm | 721 | ||
901-1000 kg | mm | 741 | ||
1001-1100 kg | mm | 751 | ||
1101-1200 kg | mm | 771 | ||
1201-1300 kg | mm | 781 | ||
Spring dimension "D" | See picture | |||
Test values for hydraulic braking system
Number | Designation | Model | ||
BE42.50-N-1002-01B | Brake fluid pressure | Permissible | bar | 3...4 |
Maximum | bar | 6...7 | ||
BE42.50-N-1003-01B | Pressure between diagonal brake circuits | Permissible | bar | 3...4 |
Maximum | bar | 6...7 | ||
Axle load-dependent brake (ALB)
Referenced documents
- ah0060n010001a Special instructions for lifting and supporting vehicle
- ah4200p000301a Notes on repairs to brake system
- ah4250p000101a Brake fluid notes
- ar4210s0010m Bleed brake system
- ar4280s160301a Adjusting pressure regulator of the ALB rear brake
- as0000z001001a Risk of death caused by vehicle slipping or toppling off of the lifting platform.
- as4250z000101a Risk of poisoning from swallowing brake fluid. Risk of injury from skin and eye contact with brake fluid