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Bell Crank Steering

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JRod View Drop Down
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    Posted: Feb/27/2013 at 8:49am
I was just going through steering systems used in quad bikes and I noticed that majority use bell cranks in their steering instead of racks. Now keeping cost and manufacturing in mind, bell cranks would be both cheaper to make and easier to design. But most baja teams use rack and pinions. Any thoughts as to whether it would be better to use a bell crank instead?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Baja Bhai Quote  Post ReplyReply Direct Link To This Post Posted: Feb/27/2013 at 9:49am
It must be because quad bikes do not require as much a steering gear reduction as a Baja car needs. Because you have a greater front axle weight. If your driver is blessed with Popeye's biceps ,then a bell crank would be a feasible idea.On a serious note, if you have to obtain the same reduction as a Rack does, then your bell cranks arms will be disproportionately long making them vulnerable to excessive bending moments. Moreover you would need a mechanism to convert the rotary motion of the steering wheel into a linear force that will have to be multiplied by the mechanical advantage of the bell crank before it finally reaches your steering arm. That is again complicating things.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Soccerdan7 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/27/2013 at 10:39am
Originally posted by JRod JRod wrote:

I was just going through steering systems used in quad bikes and I noticed that majority use bell cranks in their steering instead of racks. Now keeping cost and manufacturing in mind, bell cranks would be both cheaper to make and easier to design. But most baja teams use rack and pinions. Any thoughts as to whether it would be better to use a bell crank instead?

I believe Northeastern uses a bellcrank setup with their handlebars. They probably have some useful insight.
Danny

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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/27/2013 at 11:42am
Originally posted by Soccerdan7 Soccerdan7 wrote:

Originally posted by JRod JRod wrote:

I was just going through steering systems used in quad bikes and I noticed that majority use bell cranks in their steering instead of racks. Now keeping cost and manufacturing in mind, bell cranks would be both cheaper to make and easier to design. But most baja teams use rack and pinions. Any thoughts as to whether it would be better to use a bell crank instead?

I believe Northeastern uses a bellcrank setup with their handlebars. They probably have some useful insight.
 


I would think that their handlebars give a greater mechanical advantage from the driver's hands than a 10-13 inch steering wheel too though.
Kyle Collins
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jasper8391 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/27/2013 at 12:31pm
Bell cranks are strong, but are limited to around a 1:1 turning ratio.  Like collinskl1 said, it works well with our handlebars because of the mechanical advantage, but I can't imagine using a steering wheel with a bell crank.  Another design challenge that comes with using a bellcrank is that it moves the tie rods in close together.  Our LFS members by our feet are only a few inches apart, and so our front suspension is actually under our feet.  If you decide to use handlebars with a bell crank, then that brings a whole other set of challenges to make the frame fit around them.
Evan Jasper

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http://www.numotorsports.com/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Priyank Quote  Post ReplyReply Direct Link To This Post Posted: Mar/02/2013 at 5:10am
Bell cranks can't be used simply because we do not have handlebars.
It'd be really impractical to use a wheel with bell crank.
I mean, the entire logic of using a wheel is lost.
Racks provide amazing reduction, with smooth turning.
You never stop learning.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brat_Prince Quote  Post ReplyReply Direct Link To This Post Posted: Apr/21/2014 at 9:26am
we've used a bell crank for the past 5 years or so and it works pretty well for us, given the mechanical advantage of the handle bars. in fact our cars tend to handle a lot better than those with a rack and pinion setup.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2014 at 11:53pm
We used a bell crank setup with a steering wheel for a few years. We used 2 steering quickeners acting as reducers to get a usable steering ratio. Initially we had issues shearing teeth in the quickeners, but eventually found a setup that worked. 

Then the team went back to a rack.
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