Making universal joints

Why not just buy a socket set UJ and save a lot of work?

How important is constant velocity in your application? What sort of angulation will they have to cope with?

Tim

I just want to drag a skate along a rail, like this:

but underneath the bus instead! So I need a flexible joint on the skate and another where the pole attaches to the bus.

I looks like that skate is headed off in the wrong direction! ;-). I presume this is required when there is only a single overhead wire?

Tim

What about using some thick metal brainding - battery earth straps

Why not just use a drive shaft? I am not sure how it will cope with tension and stretching loads though.

Of course! There needs to be a detachable insulated pole so that the skate can be put in the right place. The skate is at 600v potential when lifted off the rail. The upper pole has to be removed before the skate is moved.

The joints have to have limited movement since the bus might want to go backwards for a bit. Otherwise I'd just drag the skate with a steel wire rope.

If it is too strong and the thing snags when reversing it could do very serious damage to the mountings

Use the ends of a prop-shaft from a scrapped rear-wheel-drive car?

The few operators in the UK who occasionally used that method of moving trolleybuses using tram routes used shaped iron skates connected by chain links. The appearance of this arrangement meant the device was nicknamed the "The String of Sausages".

G.Harman

Similar ones I have seen use a pair of yokes that are riveted on to the faces of a large hex nut in the centre... should be easy enough to knock up.

OK, the job's done. I found some unused 30 year old trolley pole heads. They can revolve all the way around and tilt quite a lot. More importantly, they can conduct a few hundred amps while having a flexible connection:

Err - have you *seen* Matty's previous posts? Past evidence suggests that "saving a lot of work" is not high on his agenda.