Why do some agencies and museums use trolley poles and others us pantograps? Some places like WRM in Rio vista can use both.

Thought I start off the new year and new board with this.

-Negin

The overhead conductor made the difference. Trolley wire used clamps shaped to allow the trolley pole contact to slide over them. Wires that used slots along the side of the wire allowing the clamps to sit in the slot were used for higher speeds lines and allowed the use of Pantographs.

Good Afternoon,


In regards to the clamps that hold the contact wire, usually, the clamp recieves a flat head, hex counter sunk machine screw. I noted on the Third St line, they used a hex cap screw. The trolley shoe runs deep enough on the wire, that is strikes the hex cap screws. If countersunk machine screws are used, they are flush with the clamp and the trolley shoe passes through with ease.

Muni used to have secions of round wire remaining, which the hanger was peanned over to hold the wire. As long as it was flush the shoe would pass through. A the hanger wore, it could also begin to damage the shoe and carbon.

The pantogrpah just slides along under the wire. If you ever see a PCC or trolley pole equipped car out on the L or M (or K) lines, since the pantograph slides along under the cotact wire, the trolley shoe wraps around the under part of the wire and there is a great light show. Especially at night !

I've seen videos on YT of trolleys or light rails running on super cold days under wires that are iced over. Great fireworks!