Need some tech help with electrics

I'm just building my tyre truer and was gona use a tamiya 540 STD can but it not strong enough as it got way to hot after 1 min of spinning. So I've stripped an old drill with a 14v motor.
I have linked it up without the drill switch and it's ok but the battery lead gets a little hot so im thinking I need the switch as it's got some extra wires on it with what looks like a heat sink?[img][You must be registered and logged in to see this image.][/img]

Can someone tell me what it is and if I need it to use it of the mains with a 14v plug?
Or can I use a STD switch and run it of a battery?

Here is a few pics of what I've got so far
[img][You must be registered and logged in to see this image.][/img][img][You must be registered and logged in to see this image.][/img][img][You must be registered and logged in to see this image.][/img][img][You must be registered and logged in to see this image.][/img]