spacer BSM Track Updates . . .
by
John LaCosta


Track Updates for May 17, 1998


    T his weekend has been much more normal than the ones for the last two months. Saturday morning had only one shop person available for morning work, so Rick was up at the shop getting ready for the major afternoon task. Ed was on vacation and Mark, Greg and I were involved in the training class.

     The training class was fun to do. Rick and I got to help the students, including Greg, learn about our fare collection and how to operate the cars into 28th Street loop. While we were teaching, Mark was evaluating the instructors, which is what the Chief Instructor should do. The students seem to be doing very well and I look forward to the next class I have to do in two weeks time.

     The major task for the afternoon was to start an annual inspection on 7407, the PCC. The inspection started with the trucks and as we had expected, four of the eight brake shoes needed to be replaced before next year's inspection. We also checked the backlash in the axles and have decided that two of the axles need to have the backlash reduced.

     The brake shoes are used to stop the PCC when its speed is below 8 MPH and to keep it from moving when the car is stopped. The brake shoes are held in a casting by two plow bolts. The casting (brake head) is attached to a lever, which is attached to a long rod (brake beam) that runs the width of the car. There is a brake shoe at each end of the brake beam. To isolate this brake assembly from the truck, the rod is held in two placed by rubber sleeves. A clamp and four bolts hold the sleeves. The inspection of the brakes revealed that two of the brake heads were not pivoting to allow the brake shoe to rotate and match the wheel, and two of the brakes shoes were getting too thin.

     While changing the brake shoes should be easy, it turns out that with the limited use the PCC get with just weekend service, the bolts used to hold everything together are very hard to get loose. It took Rick and Bill most of Sunday afternoon to get the two brake beams removed from the car. Next week we will take the two brake beams up to the shop to refurbish them.

     Saturday Rick also removed the pinion gear from one of the axles. The axles at first glance look like a large differential that you would find on a rear drive car. The PCC axle is solid and therefore no differential is needed. The pinion gear is connected to the traction motor using a drive shaft, again much like you would find in an automobile. The pinion gear is very interesting to look at; it looks like a cone with spiral teeth.

     While this type of gear is very had to make, it is very efficient in transferring the power of the traction motor to the axle, while is at right angles The adjustment of how far this pinion gear is inserted determines the amount of backlash in the system, Too little and the gear will overheat and too much will result in excessive wear and large shocks to the gears. Rick spent most of Saturday morning reading the rebuild book on PCC axles to prepare for the inspection and disassemble. Next weekend we should be able to adjust the shims and reinstall the pinion gear.

John

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