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Subject: 
Re: A better device for tank treads than the adder / subtractor
Newsgroups: 
lugnet.technic
Date: 
Fri, 16 Aug 2002 22:13:49 GMT
Viewed: 
3277 times
  
Thanks Dean for the great ideas and for posting links.  Sounds like I should
buy the Ferrari brothers book.  I'll try the clutch idea first, it seems to
be the solution I'm looking for and it is relatively simple, I do have a
couple clutch gears but I really like the idea of using the ribbed hose.  I
used to think ribbed hose was useless until I discovered it makes great
track for rolling marbles.  Unfortunately I'm in a softball tournament this
weekend so I won't be able to do it right away.  I'll let you know how it
turns out.  Hopefully I'll be able to borrow a digital camera so I'll be
able to post a few pictures.

> I think most of your problems would be solved by installing a clutch that
> links the left and right drive axles.  It would be somewhat like the limited
> slip differential in the Ferrari brothers book.  I perfer using the clutch
> gear instead of pulleys like they use; the pulleys introduce a lot of drag.
> 
> The clutch consists of an axle, a 24t gear and a 24t clutch gear.  The 24t
> gear engages the drive gear for the left track and the clutch gear engages
> the drive gear for the right track.  The two gears are tied together by the
> axle.  When one track starts to turn faster than the other the clutch steals
> some torque from the faster track and suplies it to the slower.  It's not
> perfect, but it works pretty well and is easy to implement.
> 
> If space is tight, or you don't have a clutch gear, you can build a modified
> version of the clutch using two axles, two gears (whatever size fits best)
> and a length of ribbed hose.  The ribbed hose hose and axles form a "Sleeve
> Clutch" (if there is such a thing).
> 
> I put an image and LDraw file on Brickshelf to show what I am talking about.
> 
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=23480
> 
> If you need to go perfectly straight you could create a locking
> differential.  There are examples of this in the Ferrari book also.  You
> install a differential where the left shaft turns the same direction as the
> left drive shaft, and the right shaft turns the opposite direction of the
> right drive shaft.  The differential housing is stationary if both drive
> shafts spin at the same rate and in the same direction.  If the speed or
> direction is not the same, the differential housing will turn.  Locking the
> differential housing locks the left and right drive shafts together.  A
> third motor attached to the differential housing via gears can provide the
> locking mechanism.  Lock the motor when you need to go straight, and float
> the motor when you need to turn.  You could even use the motor to supply
> extra power when turning.  The only problem is that turning one direction
> you speed up, and turning the other direction you slow down.
> 
> The put a bitmap showing the framework for the locking differential on
> Brickshelf also.  All you need to add is the motor.
> 
> Dean



Message has 1 Reply:
  Re: A better device for tank treads than the adder / subtractor
 
Dean, the clutch idea works perfectly! I make a simple drive base like the one in your post using the clutch gear, added a couple of motors, tested it using a couple of dual-switch battery boxes, then tested it with an RCX and a remote. It drives (...) (24 years ago, 18-Aug-02, to lugnet.technic)

Message is in Reply To:
  Re: A better device for tank treads than the adder / subtractor
 
(...) I think most of your problems would be solved by installing a clutch that links the left and right drive axles. It would be somewhat like the limited slip differential in the Ferrari brothers book. I perfer using the clutch gear instead of (...) (24 years ago, 16-Aug-02, to lugnet.technic)

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