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Looking somewhat the worse for wear, PCC No. 322 awaits restoration at the Metro Transit overhaul base in 1992. As with any half-century old steel vehicle, there was extensive corrosion.
Some seven layers of lead-based paint had to be removed. A product called Peel-Away 7 was used and all paint removed was collected in one 55 gallon drum which had to be disposed of in a hazardous waste site.
Several of the roof supports over the windows had rusted completely through where they attached to the side sill.
The most serious corrosion on many PCC cars seems to occur at the front left corner. These floor braces were just behind the motorman's podium.
Rubber matting surrounded the base of the trolley pole on the roof and proved very effective at retaining moisture. This eventually led to extensive corrosion on the roof.
All flooring was removed so that the frame could be needlescaled and painted. The frame itself was in remarkably good condition with only one minor brace requiring welding
After 5 years of restoration at the overhaul base, PCC No. 322 touches home rails for the first time in 44 years.
After another three years of restoration at MTM's maintenance facility at Lake Harriet, PCC No. 322 is ready for revenue service.
MTM contracted with Metro Transit for the bodywork and painting. Nine gallons of body filler were applied giving PCC No. 322 a Mediterranean look - salmon, turquoise, and silver.
Before painting, a half century's worth of dirt was blown out of every nook and cranny using a high pressure, high volume air hose. Otherwise, the painting process itself could loosen the dirt.
PCC No. 322 sees daylight for the first time in its resplendent coat of Twin City Lines yellow. Dupont still carried the paint number in its catalogue. House moving wheels and a dolly were used to move PCC No. 322 to the paint shop and back.
Early research showed that even standing passengers could tolerate high rates of acceleration if it was smooth. The eight acceleration points in the controller on a standard car were not smooth.
The accelerator pedal in a PCC car activates a pilot motor which turns a commutator cutting resistance in and out. A total of 136 stages are available providing very smooth acceleration.
There are four 55-horsepower motors.
The PCC car has three braking systems:
Dynamic braking is the primary braking system and is effective down to about 1 mph at which point the shaft brakes are automatically applied to stop the car. For dynamic braking, the motors become generators and the electricity generated is used to heat the car in the winter or dissipated in the resistor banks. The shaft brakes, which also serve as parking brakes, are applied by springs and released by solenoids, each of which weighs 140 pounds. Magnetic track brakes are also applied if the brake pedal is depressed far enough.
Dynamic braking utilizes the same pilot motor as acceleration except that there are 272 levels of braking. Braking rates are determined by how far down the brake pedal is depressed.
If the brake pedal is depressed to the floor, all hell breaks loose. In addition to the dynamic and shaft brakes, the magnetic track brakes are applied, the rails are sanded, a buzzer sounds, and the doors are balanced so that they can be manually opened in case of an accident.
An overhead view of the trucks from PCC No. 322. The motors, driveshafts, springs, and brake solenoids can be seen. The cardboard squares with masking tape cover the forced ventilation openings to the motors.
The driveshaft end of a PCC motor. The brake drum and the external, contracting brake shoes for the shaft brakes are visible.
The Acceleration and Braking Controller (ABC) is just one component of the complex control circuitry. This is under the floor just ahead of the center doors. The control rods from the operator's brake and accelerator pedals enter at the top of the picture, just left of center.
The PCC wheel is a rubber/steel sandwich that effectively eliminates much of the noise and harshness. Note the track brake hanging on springs above the rail between the wheels.
All photos and captions courtesy John DeWitt who is one of the many volunteers who contributed nearly 10,000 hours to the reconstruction of PCC No. 322.