by Christoph Heuer » 10.10.2010, 18:49
Hi,
there are two philosophies. One is going along the saying "if it ain't broken, don't fix it". The other is that of preventive maintenance, i.e. you maintain something before it fails and prolong its life.
Preventive maintenance, and the eight-year lifts are just that, obviously has some advantages, notably that you can avoid a potentially costly repair after a failure. Also the workshop time can be planned more easily. Imagine the chaos if three tramcars decided to fail with substantial defects in a short period and the frustration if it turns out that those defects could have been avoided by preventive maintenance.
Agreed, there are examples where cars have failed shortly after that preventive maintenance or even a full restoration, i.e. 167 and 345, strangely enough both with bearing problems. But there are also examples of cars which had just some work done but failed for another reason after a too short period of time. Look at 106 and 1297 to see what I mean.
What I do not like, though, is the strict time-based maintenance as it does not seem to be precise and in some respects wasteful.
Take the six-day exam as an example. In six days a tramcar can clock up between 120 and 156 miles, even under normal circumstances. 120 miles are six midweek-two-car-service days with ten round trips of two miles each day. 156 miles are six days with a three car service and 13 round trips of two miles each. If you take into account that quite frequently trips later in the afternoon are to Wakebridge only or cancelled altogether due to a lack of passengers or that 3006 serves as a substitute, sometimes a car might do just 108 miles, equalling six days with nine round trips each, before a service. Why should it be serviced then, if 156 miles are equally acceptable as can be seen from above?
The same applies for all routine maintenance. I believe that overhauls based on a system based on actual usage rather than time elapsed since the previous overhaul saves resources while giving the same level of maintenance. Even better, all tramcars will be treated equally, we will not have situation where some cars clock up 10.000 miles between overhauls and others just, say, 4.000.
Finally, an anecdote from Germany which happened on the railways. Here all locos must have a major overhaul after a certain mileage or 8 years. One electric loco, E 69 05 for those who are interested, managed 15 years between overhauls, since someone found out that days on which the loco was not in actual use did not count towards the eight years which were equated to 8 x 365 = 2920 operating days with some days discounted for routine maintenance. Now if we based our maintenance schedule on that I believe that few cars would be overhauled in my lifetime!
Regards
Christoph