Maintenance of Coaches and Wagons

The prescribed economic lifespan of coaches and wagons is 30 years and 40 years, respectively. Coaches and wagons go through cycles of periodic maintenance in order to ensure that they are in good working order throughout their lifespan. As stated earlier, the basic principle followed under the preventive maintenance system is that the equipment should be paid the necessary attention so that there is no wear and tear and consequent deterioration and the wagons do not become prone to failure. Some of the principles followed under such a scheme of planned maintenance are outlined here.

(a) The implementation of the scheme should be as simple as possible involving minimum amount of paperwork.

(b) A maintenance schedule must be prepared for every item that requires planned preventive maintenance.

(c) When the schedule is executed, a brief description of the action taken, the type of labour employed, and the time taken should be noted down.

Preventive maintenance, as applied to coaches and wagons on the Railways, is classified under the following heads.

(a) Periodical overhaulling in workshops

(b) Schedule and breakdown maintenance in carriage and wagon depots or sick lines

(c) Running repairs at terminals or yards

Periodical Overhauling in Workshops

Coaching stock is periodically overhauled in workshops at prescribed intervals based on the type of service for which it is used. The frequency of POH varies from 12 to 24 months. Such an overhaul consists of lifting, which involves a thorough examination of all components, and the execution of such repairs as may be necessary to enable the vehicle to remain in service until the next periodical overhaul. The prescribed intervals for the periodical overhaulling of goods stock are presented in Table 24.9.

Table 24.9 Periodicity of POH of goods stock

Type of wagon

Interval of first POH (yr)

Interval of subsequent POH (yr)

BOX wagons



Brake vans






Departmental stock, etc.



All other wagons



Schedule Maintenance

The maintenance of different types of rolling stock as per approved schedules is described below.

Coaching stock

Between consecutive overhauls, coaches are serviced in coaching depots on the basis of a schedule known as intermediate lifting. This is normally done after six months of the date of the last POH or lifting. During the process of lifting, trolleys, underframe members, the body and floor of the coaches, etc. are thoroughly examined and the necessary repair and replacement of the components of the running gear are carried out. The side bearer/centre pivot oil is also replenished. Similarly, coaching stock fitted with plain-bearing axle boxes (as distinguished from rollerbearing axle boxes) undergo the process of 'repacking' at general periodicity as follows:

Mail and express train coaches Two months Passenger train coaches Three to four months

Other coaches Four to six months

Goods stock

All axle boxes with bearings of the entire goods stock are periodically repacked at maintenance depots according to prescribed schedules. In addition, the axle boxes are packed whenever a wagon is lifted off its wheels. Roller-bearing axle boxes are attended to in workshops during overhaul maintenance.

There are a few schedules that are common to both coaching and goods stock. Some of the important maintenance work done in compliance with these schedules is the following.

(a) Vacuum brake cylinders The vacuum brake fitted on the stock must be overhauled at intervals of 18 months in the case of coaching stock and 18 to 24 months in the case of goods stock. Normally there is a separate section for vacuum cylinder overhauling in the maintenance depot.

(b) Axle boxes The axle boxes (plain-bearing) of coaching and goods stock are oiled periodically. The coaching stock on passenger trains is oiled every 15 days. A goods stock with permanently secured face plates must be lubricated with at least 225 g of oil per axle box at intervals of one month, either in maintenance depots or in the originating/terminating yards.

(c) There are many other scheduled maintenance works such as alarm chain apparatus testing, tank wagon valve testing, water tank painting, etc., which are implemented in the maintenance depots at the prescribed frequencies.

Breakdown Maintenance

The maintenance depots attend to all the breakdowns or failures of the rolling stock. Breakdowns are unusual incidents resulting either from human failure or due to the failure of the equipment. Some of these breakdowns even result in accidents.

The most common failure of a coach or a wagon is the one that occurs as a result of the axle box heating up in the course of the run, popularly known as 'hot box'. Every journal (the part of the axle at its ends, which bears the weight of the wheels) that becomes hot during the run of the train, thereby necessitating the detachment of the coach or wagon from the train before it can reach its booked destination, is considered a hot box.

There are many other kinds of breakdowns which must be attended to in maintenance depots to ensure the safely of the wagon or box.

(a) Cracked wheel tyre

(b) Expanded axle guard

(c) Bent sole bar

(d) Dead buffer

(e) Leaking water tank

(f) Wheel defects, etc.

Running Maintenance at Terminals and Yards

The rolling stock is on the move most of the time. Since the major scheduled maintenances such as overhaulling are done only when due, and call for the temporary immobilization of the stock, the normal maintenance of the stock is done in the course of its service at terminals and yards.

This maintenance mainly involves an examination or inspection of the coaches or wagons of the train and is carried out in two stages.

Stage I: At the approach to the terminal or yard when the train is still in motion.

Stage II: At the terminal or yard where the train normally stops.

The first stage of the inspection helps in discovering those defects of the undergear that are indicated by unusual sounds or disjointed/broken hanging components. For example, a flat tyre is indicated by the heavy thudding of the train as it passes over the rails. In the second stage, each coach or wagon is thoroughly examined and all defects, both exterior and interior, are recorded for rectification. Coaches or wagons found with defects that can be attended to only in maintenance depots are marked for handling there. The remaining coaches and wagons are attended to at the terminal (washing line) or in the yard itself.

Brake Systems | RAILWAY ENGINEERING - Contents | Design Features of Modern Coaching and Goods Stock