Correct usage of knob wheel

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pepijndevos
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Location: Gelderland, Netherlands
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Correct usage of knob wheel

Post by pepijndevos » 05 Oct 2013, 13:58

When is it appropriate to use this guy instead of normal gears?

Image

My understanding is that it's stronger, but that the output speed is uneven in relation to the input speed, which is why I'm surprised to see it in the steering gear train of the RAC3TRUCK by Laurens Valk.
-- Pepijn
http://studl.es Mindstorms Building Instructions

inxt-generation
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Re: Correct usage of knob wheel

Post by inxt-generation » 05 Oct 2013, 14:01

The proper use is in a situation where two 12th double bevel gears or two 20th bevel gears would snap, I think. The wear and output can be uneven, but usually only under high-torque situations. I suspect it's usage in "RAC3TRUCK" is because the EV3 retail doesn't have enough other gears, or bevel gears would slip in that arrangement.
A.K.A. NeXT-Generation.
"A kingdom of heaven for RobotC now has recursion!"

mattallen37
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Re: Correct usage of knob wheel

Post by mattallen37 » 05 Oct 2013, 15:38

I use them where normal gears would slip (spacing slightly off, or high torque). Despite their odd appearance, they actually function surprisingly well.
Matt
http://mattallen37.wordpress.com/

I'm all for gun control... that's why I use both hands when shooting ;)

laurensvalk
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Joined: 29 Sep 2010, 15:24

Re: Correct usage of knob wheel

Post by laurensvalk » 12 Oct 2013, 12:43

I used knob wheels in the gear train so that two 12z gears would be left over in the EV3 set. Combined with the 36z gears, builders can use them to make the truck actually 'race'. I've omited a technic pin in the rear to make it easy to add an axle (that's not a 'bug').

The design could have been much simpler, using fewer gears, but I wanted to make the steering wheel turn whenever the car steers.

I just realized I had an account here. Edit: It's actually my first post. :)

Laurens

pepijndevos
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Joined: 28 Dec 2011, 13:07
Location: Gelderland, Netherlands
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Re: Correct usage of knob wheel

Post by pepijndevos » 13 Oct 2013, 09:13

Ah, nice to hear the rationele of the designer himself :-) I didn't even notice there was a pin missing, but you're right.

I see how i's great for racing, but for paralleel parking I might actually redo the front section without the steering wheel to decrease the tolerance. It could greatly improve the dead rockoning of my prescision movements.

Overal I really like the truck though :-) I have added a trailer based on the NXT LEGO. I'll post pictures and videos sometime.
-- Pepijn
http://studl.es Mindstorms Building Instructions

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