Break Solution for Chain and Sprocket Mechanism 3

[Helepolis]

Hi,

I'm trying to come up with a low-tech and simple breaking solutions for a chain and sprocket mechanism.
The mechanism itself is very simple, it suppose to pivot an arm to different positions (bi-directional) and is comprised off a driven and driving sprockets connected with a chain and a tensioner and I'm trying to come up with an idea for stopping the driven sprocket from transferring forces from the arm back to the driving sprocket while the system is static (and not to maintain the arms position so it doesn't have to be too precise).

Thanks.

 

[tygerdawg]

Suggest you start by accurately specifying the torque you wish to hold, AND your desired method of actuation (manual, electric, pneumatic). That dictates the type of solution.

Possible ideas are adaptations of bicycle brake mechanisms (rim clamp, hub brake, or disk brake).
Simple wrap-around friction brake systems or mechanical ratchet & pawl systems.
Or industrial power transmission brakes & clutches like these

http://www.warnerelectric.com/products

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[drawoh]

Helepolis,

Do you mean braking?

--
JHG

 

[MikeHalloran]

Simplest thing that comes to mind, if you can tolerate the discrete positioning, is a ring of drilled holes in the driven sprocket, engaged by a 'shot pin', basically a retractable pin, fixed to stationary structure, that is advanced into one of the holes to lock the sprocket. Some kinds of toggle clamps can work for this, or just use a hitch pin through drilled ears near both faces of the sprocket.

Some ancient disk brake systems had parking brakes that jacked the service brake pads against the rotor with a mechanism built into the service piston, but they fell out of favor because of complexity and corrosion.

You could use something as simple as a C-clamp squeezing the driven sprocket, with the clamp frame attached to something stationary.

... all depending on the load, not specified.


Mike Halloran
Pembroke Pines, FL, USA

 

[dhengr]

Helepolis:
I assume the drive chain wraps around the driven sprocket by 180-190̊, leaving some clear/open sprocket circumference and teeth btwn. the two parts of drive chain. Make a shear key/bar/plate with the cut out shape btwn. two or three sprocket teeth on one edge. This is spring loaded, and pulled back to clear the sprocket when the sprocket is operating, and released to engage the teeth when you want the sprocket holding action. This shear key is supported by two vertical plates on either side of the sprocket, assuming the sprocket is vert. and parallel in its plane to the two reaction plates. What you attach the two reaction plates to depends on your machine structure and torque req’d. How you actuate the shear key and lock it down depends on your imagination.

 

[dvd]

From the motorcycle world -

http://www.performancemachine.com/m...rear/custom-brake-systems/sprocket-brake.aspx

One could adapt to apply brake pressure when the drive is powered down - looks cool, too.

From the industrial sector -

http://ipaper.ipapercms.dk/SvendborgBrakes/product-overview/

spring applied hydraulic release

 

[Helepolis]

Thanks a lot guys, that's why i love this forum!

I did all the calculation to ensure the structural integrity of the drive mechanism and i thought about designing a simple brake for the driven sprocket.
I like your idea

I assume the drive chain wraps around the driven sprocket by 180-190̊, leaving some clear/open sprocket circumference and teeth btwn. the two parts of drive chain. Make a shear key/bar/plate with the cut out shape btwn. two or three sprocket teeth on one edge. This is spring loaded, and pulled back to clear the sprocket when the sprocket is operating, and released to engage the teeth when you want the sprocket holding action. This shear key is supported by two vertical plates on either side of the sprocket, assuming the sprocket is vert. and parallel in its plane to the two reaction plates. What you attach the two reaction plates to depends on your machine structure and torque req’d. How you actuate the shear key and lock it down depends on your imagination.

, i think i'll use it with a solenoid to disengage, and a spring to engage the brake.

And yeah, sorry for the spelling, not my native language .