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Anyone out there in tech land have any ideas or plans to build a 12volt powered jocky wheel for a caravan?

What size motor would I need to move a 950 kg caravan and what size gear sprockets would be best to drive the chain to the wheel.It would have to be able to be put in forward and reverse mode.anAny advise would be of use but some plans would be the best.Thanks hoplite?

frollard7 years ago
You'd likely want to run a dc gear-motor, with a motor driver, controlled by a motor controller.  Chain driving the wheel would be quite simple - a 950kg caravan doesn't need to move very far/fast with a jockey wheel, and with wheels friction is extremely low, thus power requirement is quite low.

The DC gearmotor needn't be huge - something akin to a wheelchair motor would be plenty strong enough.

The Driver is sometimes incorporated into the controller - other times it not.  The driver does the actual switching of power to and from the motor.  (high current control)

The Controller simply takes user input (or other input) and spits out control signals to the driver circuit.  It is the smarts if such a thing exists.  (low current control).


The simplest version of a controller -- Very simply reversing can be accomplished with an H-Bridge.  <see attached>.  It uses a highish current dpdt switch to apply both possible polarities (+- for forward -+ for reverse)...
dpdt.PNG
caesar66 (author)  frollard7 years ago
Hi Frollard.

Thank you for your input I will try to get a hold of a wheel chair motor from somewhere and have a go.
Thanks again.