Recently a friend dropped off 3 postwar Bascule bridges , 1 prewar. 1 postwar complete and 1 prewar in parts. He said he had no luck trying to get them to work. I've fixed a few in the past mostly servicing the motor, replacing bad wires, adjusting the layered contact assembly and the spring. Part I try not to mess with is the ears on the shaft which runs thru the bridge To me this is the key component, in the wrong position it impossible to get it to work.It is a lot of work to disassemble the bridge and put the ears in the right position. Iv'e gotten a lot of literature on the bridge and nowhere have I seen a photo of that assembly. I do know they should be at 90o. Thanks to the article by R.J. Luppold The reason for this discussion is the lack of power from the motor (After 70 or 80 years is this a surprise for a accessory that was under powered in the first place) Has anyone tried to have the field rewound ? When I see armature, coils and fields that have that burnt look from overheating you know they are not working as intended. I know we get armatures rewound and the're like new. Why not the field? Or has anyone tried to replace the whole motor? Just things to think about. Once again thanks to all who contribute to this discussion.
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When you say lacks power, do you mean too slow to raise?
I would say your counter balance spring is not strong enough 313.77 I think. Can you tighten any more? The spring should make it almost even weight for the motor to work less.
The ones I've worked on I ended up filling the counterweight with BBs, held in place with wax. Made them almost balanced.
Thanks for the suggestions. I wonder if Walmart still sells BBs
Another suggestion might be the "lead" weights that are put on tire rims. You can get them in different sizes and get the stick-on ones. you could add what you want to the 313 and when your happy with the results just stick them.