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Road and workshop
Page 44
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by Handyman
Manpower, maintenance
and the MoT (1 7)
• A driver moving to air-braked equipment from, say, hydraulic systems where there is always a brake of sorts, even if unboosted, should be told the limits of the reserve air supply. Remember that it is one thing while undergoing garage tuition to be shown the number of pedal applications that will bring in the warning system, and another matter to do the right thing in thick traffic.
Although a driver on the new dualsafety systems of plated equipment should never find himself in trouble, a vast number of single-line air systems is still in use and it is these vehicles that may catch out the unwary new driver. This is no reflection on the single-line air system, but a driver descending a long hill in thick traffic may be caught out despite warning buzzers, signal arms, etc., unless he is drilled in advance to guard against this feature.
The driver inching his way downhill fully laden, nose to tail with other traffic, may find it easier to stay in neutral and let the vehicle roll downhill for each move, checking it with foot pedal as needed. However, with the .engine at idling speed, the air consumption can begin to beat the compressor, and unless he has an eye on the air gauge, the buzzer may suddenly sound. Unless he acts quickly he will find his pedal dead and the veh icle rolling onwards, but discover this too late to make effective use of his mechanical handbrake.
As each new driver is given road tuition, it is wise to demonstrate this downhill braking hazard on a safe slope, bring in the warning systems and check whether one, two, or more further stops can be made before air boost is lost. The driver should also be shown the handbrake application time factor, particularly if it is of the progressive ratchet type.
The driver should be taught to stay in gear for each downhill traffic move, and if air is being consumed quicker than it is being compressed, he should use each stop to increase engine revs in neutral and gain pressure until clear of the hazard.
On main roads in hilly terrain there is a tendency to drop down quite steep and twisty hills in the highest gear, just because the brakes are always powerful enough to check or stop the vehicle. . And, if in the highest ratio the engine speed is too low to keep abreast of air consumption, a steep hill is no place to find this out. Teach drivers that under these circumstances they must always drop down a couple of gears in good time for the descent, to keep the revs up and the compressor well on top of its job.