Can anyone explain why a brake pipe leakage test is undertaken after making an approx 100kpa reduction and cutting out the feed valve rather than cutting out the feed valve when the brake pipe is fully charged at 500kpa?
Thanks.
Hi,If you consider a train coming down a mountain, recharge time is a critical factor(the time it takes to get from 400 to 500 kpa) hence you are more concerned with the integrity of the brake pipe, when the brakes are applied.
Can anyone explain why a brake pipe leakage test is undertaken after making an approx 100kpa reduction and cutting out the feed valve rather than cutting out the feed valve when the brake pipe is fully charged at 500kpa?
Thanks.
Hi,Its been a long time since I worked as a driver. Two aspects need to be considered and they both relate to the type of BV fitted to the loco, but both were similar with the prospect of a different result.
Can anyone explain why a brake pipe leakage test is undertaken after making an approx 100kpa reduction and cutting out the feed valve rather than cutting out the feed valve when the brake pipe is fully charged at 500kpa?
Thanks.
Hi,The simple answer.
Can anyone explain why a brake pipe leakage test is undertaken after making an approx 100kpa reduction and cutting out the feed valve rather than cutting out the feed valve when the brake pipe is fully charged at 500kpa?
Thanks.
Because the "relay" equipment on modern trailing rail vehicles uses the BP as a constant supply of air to maintain against a BC leakage on each vehicle if there is a leak. In other words, once the BP is reduced, the BP is only acting as a set air supply to maintain air to the Aux Res if air is leaking from the cylinders on the wagons.But only on loco's with a pressure maintaining feature, so basically those carrying 26L or newer equipment. The 48's and other's with a B7 without the PM functionality require handbrakes to be applied if detained on grade beyond 10 minutes.
And more other words - if you dump the air from a train with loco attached, the wagon brakes will leak off and not be maintained. If you give a set BP application of only 100, the BP will maintain the wagons against BC leakage and the brakes will stay on as long as the loco compressor works.
Most, but not all. I work with some brand-new (well, less than 18 months old, now) wagons and they are BP-only. Even supposed "two-pipe" wagon's do not always have a suitable connection between the BP and MR, as was found in the El Zorro runaway down the Illawarra a few years ago.modern trailing rail vehicles uses the BP as a constant supply of air to maintain against a BC leakage on each vehicleModern vehicles use main reservoir as a constant supply.
modern trailing rail vehicles uses the BP as a constant supply of air to maintain against a BC leakage on each vehicleModern vehicles use main reservoir as a constant supply.
We've disabled Quick Reply for this thread as it was last updated more than six months ago.