spacer BSM Track Updates . . .
John LaCosta

Track Updates for May 17, 1998

    I hope everyone's Memorial Day weekend was a pleasant one.

     I forgot to mention that the previous week Greg and I decided to grease both loops. With all the rain we had had for the past couple of weeks, the water in the guardrails was enough of a lubricant to keep the friction low enough. For those not familiar with the loops, the curvature is very sharp, so sharp that the cars would derail if it was not for the design of the "guard" rail used in the loop.

     Actually I should first explain how the cars go around very gentle curves. If you were to look carefully at a wheel on a streetcar, or railroad car, you would notice that the flat part of the wheel is not parallel to the axle. The wheel has a slight taper such that it is bigger in diameter near the flange (toward the center of the car), and smaller diameter toward the outside end of the wheel. This slight difference in diameter will automatically "steer" the wheel around very gentle curves at slow speeds. In many cases the flange never touches the inside of the rail.

     But not all curves are gentle, so as they get shaper the flange slides up against the inside of the outer rail. If the curve is not too sharp, the wheel will squeal as it goes around the curve. As you might imagine, this tends to wear away both the flange on the wheel and the rail itself. At some point the radius can get so tight that the flange on the wheel will climb up the inside of the outer rail and derail.

     The solution to
this problem was to put a guardrail inside the inner rail, making it higher than the normal running rail. As the wheel goes into the curve, the back of the inner wheel comes in contact with the guard rail before the flange comes in contact with the inside of the outer rail. Since the guardrail is higher that the regular rail, the curve can be much sharper before the inner wheel will climb over the guardrail. But, all the while the wheel is going around the curve, the backside of the wheel is rubbing on the guardrail. To minimize the wear of both the rail and wheel, and reduce the likely hood of a derailment, the loops should be greased.

     Now back to our greasing of the loop, it is a very simple job, just put a think layer of grease on the guardrail so that only the backside of the wheel will touch the grease. One thing is for sure, by the time you finish greasing both loops, you would not want to shake hands with anyone who was clean.

     Now to Memorial weekend.

     The shop started working this past Friday evening while a local group chartered the Museum. My wife and I were part of the transportation crew, along with Ben and Carl that provided rides before and after the catered dinner. Cath and I had a very good time giving the guest rides on the cars and I think the guests had a good time as well, they were a fun group of visitors.

     As the charter was in progress, Rick, Ed and Greg continued to work on the PCC. They removed the two brake beams from under the car and started to determine what needed to be fixed. This process continuned for the next three days. By Monday afternoon, the brake beam from the front truck was ready to install back on the car and the other brake beam only needed one pin to be moved an cleaned up. Both brake beams have new brake shoes.

     Sunday was a good day for passengers and everything seemed to work fine.

     Monday Rick installed the pinion gear back in the axle and adjusted the shim pack to reduce the backlash to an acceptable amount. We will have to fine a source of shims for the other axles since Rick used the only spare shim available for that pinion.

     While Rick was busy with the pinion gear, Mel, Jerry and Carl took the Witt to 28th Street Loop to cut the trees and bushes back from the track. The spring growth was so great that is was almost impossible to send car around the outer loop. While we normally don't send cars on the outer loop, it is used when two cars have to pass each other at 28th Street. Trimming also reduces the scratches to our cars paint and increases the operator's visibility.

     The line crew was also busy Monday. Ed and I first replaced the insulators on the power feed span at the substation. I was told that this span came from the transit company's Gwynn Oak line, which means that it was at least 35 years old. After the power span insulators were replaced, we removed some trees that had fallen on our communication line between the 22nd street shop building and the Visitor's Center. We then went up to 27th Street and adjusted the trolley contactor, it was a little too tight and was pushing the trolley wheel of the wire.


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