rack and pinion question

[eloid]

is there backlash in rack and pinion and if so how to control it?

[eloid]

for rack and pinion machines which use either a 3.6:1 or 7.2:1 gearbox
how many teeth per gears is recommended.

As a observation on commerical machines ,,,,use larger number of teeth?...
i concluding 30-tooth gear gives smoother operation and much longer spur-gear life. For a non-geared motor, use 20-tooth spur gears?.

[rustamd]

In my opinion you need spur gear to be big enough to have at least 3 teeth engaged at all times, the more teeth are engaged, the less the gear would want to jump out of rack(with proper load on it of caourse)

[jcc3inc]

Sir,

For rack and pinion systems there are several considerations:

1. Use 20 degree rack and pinions

2. While I prefer 24 dp (diametral pitch), 20 dp rack is readily available from www.stdsteel.com/gear.htm

3. Matching piions can be had from Boston Gear, Martin Sprocket and others. Use AT LEAST 18 teeth on the pinion; we used around 30 teeth for better number of teeth in contact

4. Spring load the pinion into the rack with a force of (.37 x the max drive force expected).
For example, if you expect 50# force, the spring should push the pinion into the rack with 18# of force.

5. Set your pivoting point for the above mechanism so that it falls on the pitch line of the rack. This will result in equal pinion-to-rack engagement forces for driving forward or backward.

The gear reduction you choose depends upon whether you use servomotors or steppers, the number of microsteps you use, the force required, the system mass, and the expected max cutting force requiored for your application.

Regards,
Jack C.

[edco78]

Take a look at this site: http://www.nexengroup.com/nexen/prod...duct?pn=966600

[rustamd]

Originally Posted by edco78 Take a look at this site: http://www.nexengroup.com/nexen/prod...duct?pn=966600

thats one expensive option

[harryn]

jcc3inc - thank you for that very clear summary. It certainly helped me.