APSRTC O/o the VC & MD, Mushirabad—Hyderabad,

No.OP2/255(5)/93 MED Dt. 20-02-1993.

Circular No. 7/1993 MED., Dt. 20 02 1993.

SUB:—MAINTENANCE - Preventive Maintenance Schedule for brake System on Ashok Leyland Vehicles - Reg.

Ref:—Preventive Maintenance Schedules communicated vide this Office Lr. No. OP4/ 391(1) / 87-MED, dt. 1-4-1987.

Despite clear instructions issued vide the letter at reference, it is observed that many of the Depots are carrying out breakdown maintenance instead of preventive maintenance, particularly in respect of brake system. To support this, following are the few observations made during the inspection of depots.

a) Air pressure gauges are not in working condition and pipe lines disconnected.

b) Air brake system pin setting was found to be higher than recommended.

c) Brake diaphragms are not being changed till they become unserviceable.

d) Filter element air filter fitted in Air Tank is not being cleaned till it becomes ineffective.

e) 'L' hose between the inlet manifold and the compressor is not being replaced in case of deterioration and they are not even clamped.

f) The condition of brake pedal mounting including pivot pin and roller pin is not being checked till it fails.

g) Rubber hoses are not checked for abrasions, swelling and other damages.

h) El valve and unloader valves are not getting overhaul/replaced at recommended intervals, i) Fail safe system was found disconnected by loosening the wine off Nut of spring brake actuator.

Brake system is one of the most critical item of all the various systems of the vehicle. In the absence of any preventive maintenance being carried out the entire braking system is rendered ineffective leading to disasters. Reliable brake system is very vital for the safety of the passengers and the vehicle. There are clear instructions for carrying out complete inspection of the brake system in Sch.III & IV. From a sample survey of the practices obtaining at various depots it is seen that these instructions are not strictly being complied with .

It appears that a kind of breakdown maintenance is carried out in this regard and many supervisors are content with this practice as it has worked effectively for more than a decade. It is also true that the practice has been quite satisfactory. Never the less, we cannot take chances with safety and it is necessary to enforce preventive maintenance, as a measure of abundant caution. In this regard a simplified preventive maintenance schedule is prepared and enclosed to this Circular for strict implementation.

For all .subassemblies such as Unloader Valve, El Valve, Dual Brake Valve, System protection Valve, Slack Adjusters. Graduated Hand Control Valve and Scoring Brake Actuators etc. adequate floats may be kept at the depot stores obtaining the sanction of the competent authority. This is necessary since the subassemblies are required to be replaced at prescribed intervals.

For having carried out of the assembly-wise maintenance schedule at the prescribed intervals, a record may have to be maintained either in a separate register or in the register being maintained for Sch.III, IV and F.C.

The Sr. Engineer /Divisional Managers shall in co-ordination with the Sr. Engineer (Works) ensure provision of adequate float sub-assemblies to the depot depending on fleet strength. They shall also ensure that the prescribed preventive maintenance schedule of brake system is being implemented by checking the records and having physical inspection of vehicles during their inspection of depots.

This Circular supersedes the earlier Circular (i.e.) Circular No. 6 / 1987-MED dt. 1-4-1987 issued.

Sd/-

(CH. RAGHAVENDRA RAO)

Chief Engineer (Mech.)

PREVENTIVE MAINTENANCE SCHEDULE ON AIR BRAKE SYSTEM OF ASHOK LEYLAND VEHICLES