SM42.20-L-0007A | Check compressed air system | 18.2.99 |
MODELS 668.###, 670.### ## up to 070980
except CODE (B16) 2-circuit hydraulic brake/2-circuit compressed air brake
except CODE (B19) hydraulic 2-circuit/compressed air 2-circuit heavy-duty brakes
N42.20-2026-01
Figure 1
P1 Test connector
Fig. 2
P2 Test connector
1 Adjustment screw
2 Overflow valve
N42.20-2033-01
N42.20-2034-01
Fig. 3
V2 Boiler 2
B12 Switch
Figure 4
P3 Test connector
N42.20-2035-01
N42.20-2041-01
Figure 5
B13 Switch
B14 Switch
B74 Switch
B75 Switch
Modification notes
Operation no. of operation texts or standard texts and flat rates
Range | Op. no. | Operation text |
N | 023721 | CHECKING OPERATION AND TIGHTNESS OF COMPRESSED AIR SYSTEM |
| Testing | ||
1 | Check readiness lamp | Measure pressure at test connection P1 Switch on using switch B13 when pressure drops below 5.8 bar 0.3 bar. Switch off using switch B14 when pressure rises above 8.4 bar 0.4 bar | |
2 | Pressure supply lamp at boiler V2 (Figures 2 and 3) | Measure pressure at test connection P2 Switch B12, on/off switching point 5.8 bar 0.3 bar | |
3 | Depressurize system | ||
5 | Attach 2 pressure gauges to test connections P1 and P2 | ||
6 | Measure overflow valve setting | Measure pressure at which overflow valve opens and fills boiler V2. Specified value 9.6 bar - 0.3 bar | |
7.1 | Make overflow valve setting by adjusting screw | Only if there is a difference | |
8 | Check parking lamp "P" (figure 4) | Measure with handbrake off, test connection P3. Switch B5, on/off switching point 5.8 bar 0.3 bar | |
9 | Check compressor on/off switching points | Read off pressure at test connection P1 Switch B75, compressor switch-on point 10.5 bar 0.5 bar Switch B74, compressor switch-off point 12.0 bar 0.5 bar | |
10 | Check compressed air dryer drain valve | After the ignition is switched on and the compressor switched off, the drain valve opens for approx. 4 sec. | |
When carrying out conversions in the winter months, ensure that any condensation that is present is | |||
11 | Operate drain valves several times and also pour approx. 5 ccm of antifreeze (Wabcothyl) into the pressure circuit downstream of the air dryer | The antifreeze must not be poured in upstream of the air dryer, since this may destroy the air dryer. |