Calculating Speed for a Mechanical Dolly Driven by Electric Motors

[fanning21]

Hi there,

I have recently been working on a project that involves building a mechanical dolly that is driven by 2 electrical motors.

I have decided to use 2 electrical winch motors which each have a rating of 5700kg and a drum size of diameter 64mm

My question is, how do I calculate the speed of the vehicle if I am planning on using 18" wheels.

Do i need to calculate the rotational speed of the drum first?

I need this information in order to decide which sized sprockets I am to use.

Thanks!

 

[Lazer57]

Using the rating and the drum diameter you can find out how much torque it will produce (you'd only need this to confirm that the motors are strong enough to power your dolly for a certain vehicle weight and/or certain incline). You'll have to find out what the rpm of the drum is either via the description or by testing it out. You know the wheel size and you'll have to decide what vehicle speed you want so you can pick out the sprocket based on that. Or if there is a maximum sprocket size that you can put in your design or that you wouldn't want to exceed you can choose than to find the vehicle speed. I'm a little confused about how exactly the motors will be driving the motorized dolly. Are you going to attach sprockets to the wheel shaft and the motor shaft? Or are you going to attempt to make the wench cable go around a pulley to turn the wheels? Or something else? Maybe a simple drawing would help.

 

[russ_watters]

If you have the horsepower/kW you can calculate the speed.

 

[fanning21]

Thank you for the quick response, and sorry if my explanation was not too clear!

My plan was to attach one sprocket to the winch drum and another one to the shaft in order to drive the wheel..

My issue was deciding on the ratio of the sizes of the two different sprockets. I first calculated the RPM of the drum using the diamater and line speed. Then I calculated the RPM of a 19" wheel with a speed of 3 km/h

Basically both RPM's are roughly 33rpm which means that both sprockets must be the same size!

Does this make any sense??

 

[Lazer57]

Thank you for the quick response, and sorry if my explanation was not too clear!

My plan was to attach one sprocket to the winch drum and another one to the shaft in order to drive the wheel..

My issue was deciding on the ratio of the sizes of the two different sprockets. I first calculated the RPM of the drum using the diamater and line speed. Then I calculated the RPM of a 19" wheel with a speed of 3 km/h

Basically both RPM's are roughly 33rpm which means that both sprockets must be the same size!

Does this make any sense??

Yup, that makes sense. The sprockets would be the same size since the rpms wanted for the wheel shaft and what the winch produce are the same. Good luck with your project.