Ever seen a TV live truck on scene? Well, if you have, chances are you’ve noticed a thing on top that looks like the top of Crow T. Robot’s head on a tall extendable mast.
What you’re looking at is a foldable microwave dish that can be used to send video from a live shot back to a fixed receiver site that forwards it to the TV studio. At the bottom of it is a remote controlled pair of big chonky motors that let you, standing on the ground, pan or tilt the dish to get it lined up with the receive site so the station can see your live shot coming in.
One of ours got stuck in the up position so I needed to pull it apart and fix it and I intended to take some more pictures of the apparatus as it’s kinda cute – it has two big Bodine gear motors driving worm screw drives via little drive chains, and has limit switch cam assemblies to keep you from going past safe travel limits on the thing.
I found the issue pretty soon after figuring out how to open the weird chassis of the dish motor, which opened vaguely like a milk carton – a hinged milk carton made of sheet metal. I’ve never seen anything quite like that and have to give them points for originality, though, if you had to get in there and the dish was stuck in a position other than straight up, you’d have to disassemble the entire shebang from the sides and take the dish off and everything and eww.
Thankfully, this was stuck straight up, and Tina caught a couple pictures of me working on it after I got it open:
But then the gloop went off.
See, what happened was one of the motor brushes got stuck in the brush holder and wouldn’t advance as it wore down a little, which caused the motor to stop working open circuit. I pulled it apart and managed to get this picture before I realized….. whoops, the armature of the motor and its pressed on bearing were the only thing holding the gloop in. You can see the brush on the right still wedged back in the holder where it can’t actually touch the commutator:
The gloop I refer to is a particularly foul, stinky, sticky, syrupy sort of gear oil, almost all the way up to being a grease in viscosity, but just low enough in viscosity to allow it to make a huge mess in short order. This is the second time I’ve run into it on Bodine motors – there’s no externally visible sign of it having an oil filled gearbox, no fill/drain screw or plug, nothing. You just get a terrible surprise if you dare separate the motor from the gearbox. GLOOOOP.
A fair amount escaped and got all over everything, but there was certainly enough left in the gearbox immersing its guts that I don’t feel I need to disassemble the whole thing and try to refill it. Nah, it’s just a learning experience… AGAIN…. BEWARE THE GLOOP.
Otherwise it will get the song stuck in your head. That song never leaves…. not that it ever has to.
There’s an extended version too