Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: Mastermime on September 22, 2012, 10:04:30 PM

Title: How to prevent possible track derailment
Post by: Mastermime on September 22, 2012, 10:04:30 PM

Hello everyone,

I am worried that my treads on my robot will derail when moving at high speeds (5 mph or more).  When I move the treads with my hands, they seem to move more and more off the idler wheels. The spring loaded idler and the drive wheel appear to be slightly different angles when I observe, but when I aligned the components, I made sure they were straight.  Any suggestions on how to prevent this derailment?

Thanks

J

Track image below
https://docs.google.com/open?id=0B83RdnxAI6xvNGVrWVM0dGY2NzA (https://docs.google.com/open?id=0B83RdnxAI6xvNGVrWVM0dGY2NzA)

Title: Re: How to prevent possible track derailment
Post by: Gertlex on September 23, 2012, 10:29:45 AM

It seems like guard plates on the sides of the tracks would be a good approach.  Fixed ones at the top of the loop for sure, and you could do spring loaded ones at front/back so that you can still roll over large-ish obstacles.

Title: Re: How to prevent possible track derailment
Post by: Mastermime on September 23, 2012, 07:07:13 PM

Ok thanks for the response.  I think definitely a guard plate at the top of the loop in the middle and then guards on the bottom idler wheels.  That would give the wheels two points of support too.  What's your thoughts on that idea?

Title: Re: How to prevent possible track derailment
Post by: Gertlex on September 24, 2012, 04:59:40 PM

I'm not sure I see how you could put guards anywhere on the bottom without them hitting the ground? (assuming you're going over non-flat terrain some of the time.)

Title: Re: How to prevent possible track derailment
Post by: Mastermime on September 24, 2012, 05:43:27 PM

Yeah that's true  :P 

I did a quick photoshop of the picture to add in the chain guard.  Is this what you envisioned?  I would have to make vertically long enough so that when the robot travels over terrain and the track adjusts, it wont obstruct the tread movement.



https://docs.google.com/open?id=0B83RdnxAI6xvMDRrdS0yclNJWTQ (https://docs.google.com/open?id=0B83RdnxAI6xvMDRrdS0yclNJWTQ)

Title: Re: How to prevent possible track derailment
Post by: Pogertt on September 26, 2012, 07:13:06 AM

Adding a pair of idler pulleys(Red), and wraping the belt(Blue) may work.

Use idlers that have flanges as in pulley circled in yellow.

Title: Re: How to prevent possible track derailment
Post by: Mastermime on September 26, 2012, 04:59:16 PM

Those are some good ideas, but the only problem is the tracks and idlers (with flange) were expensive and I don't have the money to buy a new track ($100 each) and more flange pulleys ($40 each) because I'm a high school student.  Good ideas though

Title: Re: How to prevent possible track derailment
Post by: Pogertt on September 27, 2012, 12:03:43 PM

Plan B...............
If you were to re-fashion your lower wheel brackets, making both left and right hand guides, this may be a less expensive solution.

Title: Re: How to prevent possible track derailment
Post by: Mastermime on September 29, 2012, 01:04:30 PM

Here is my proposed solution.  Tell me if you guys see any issues with the picture below

The guards on the idler wheels will extend out the front and back acting as a guide for the tracks

https://docs.google.com/open?id=0B83RdnxAI6xvWnJoaFhWSnVmdnc (https://docs.google.com/open?id=0B83RdnxAI6xvWnJoaFhWSnVmdnc)

Title: Re: How to prevent possible track derailment
Post by: Pogertt on September 30, 2012, 09:16:55 PM

@ Mastermime..............

I would offer that you should put the extension on both the outer side of the ground wheels, and also put extensions on the inner sides to prevent the tracks from falling inward.

Title: Re: How to prevent possible track derailment
Post by: Mastermime on September 30, 2012, 10:04:25 PM

Ok thanks for your help Pogertt