Pulley System for a Remote Control Camera Dolly

Man power, simple reliable, few hazards.

After that, electric, but then there are hazards... and more stuff to go wrong.

I don't know the technology involved, but I can give you a place to look. I saw the same thing being done at an NFL game.

Hydraulic motor would work well for this application.Power source could be isolated from drive system and noise would not be a factor.Also an advantage would be that the flow could be controled to adjust speed.

I wouldn't suggest a hydraulic motor. It would be far to cumbersome for this application. Your camera system will determine the weight required for the dolly. The speed you want to acquire would require a very long rail system. Check out William F. Whites or Panavision or look for the Fischer 10 dolly for more ideas to do this properly. Electric would be my choice though and no pulleys- recipe for disaster. This comes from over twenty years in the film business.

My suggestion is to use a non-pulley system, either rack and pinion or mount motor on dolly and use a friction drive system similar to what roller coasters use. Rubber wheel which makes contact with a guide rail and motor would power dolly back and forth along guide rail. You would probably also need limit switches at each end of the guide rail to reverse motor direction if you want this to be fully remote controlled. Also for safety, you should add one helluva big chunk o' metal at each end of the guide rail to act as a safety stop since you want a speed of 25-30 km/h. Cover stop blocks and a patch on the dolley with some UHMW (Ultra High Molecular Weight) plastic to soften the stopping action. You will also need a way to stop this sucker in case you lose power or need it to stop very quickly at a certain point along the guide rail. Use a magnetically coupled brake which will engage when you lose power to the dolley drive or can be intermittently interrupted with a push button switch/remote control switch at any point along the guide rail.

Oh, don't forget to patent it when you're done.

I would recommend looking into linear motors. They have the advantage of being able to generate high acceleration (and therefore high deceleration) and, perhaps more importantly, they have no moving parts.

With no moving parts they will not cause mechanically induced vibrations (such as a rack and pinion would, or a rotating motor might) and wont suffer from friction induced wear.

Chris

Linear motor??? Never heard of such an animal. Got a link to them?

Thx

Here's one link http://61.236.112.50/hrbn/Products/index1-3.htm that will get you started.

Brad

Thanks Brad

I would like to use pulley, over friction or any other way as it will hold the buggy onto the track meaning less chance of it coming off especially at higher speeds. Also the way that I have made the wheel units, make it very difficult for any powering from the camera buggy.

I was thinking of using a power-off brack that would activate if the power was cut for any reason, and attach this somehow to the pulley drive system. A limit switch would be great, but I havnt been able to find a one-way switch as of yet. As you can guess it would need to be stopped going one way, but alowd to travel the oposite direction back.

Electric would also be better than hydraulic in my opinion as should anything break, there would be less mess involved.

What is the distance that the camera will need to travel?

I have currently 25ft of track in 5ft sections with the addition of 2x 2-1/2ft sections to mount the pulley system on at each end of the track.

I was asking because some (somewhat) long-range camera tracks use the skycam system and it works beautifully (Football, F1 racing, etc) but are obviously very $$$. How accurate does the movements need to be? An electric motor with limit switches will do fine but I would go for a servo motor if precision and acceleration/deceleration are important factors.

anyone? got any ideas?

It depends on how heavy the dolly is that you using. I usually work with light weight dollies that I buy from www.mollymfg.com For somthing under 150 lbs I think an electric motor would be the best. You can even us a small electric motor with a gear box that would give you extra torque and a nice smooth movment. You could even set it up so you can control the motor speed with and acutally RC controller.

rope