rack and pinion

[delb]

i have been using straight cut teeth rack and pinion,wanted to explore the idea of helical gears.wat can be the pros and cons of it?what calculations involved in it?

[Vinnie]

hey delb,

I have looked at it in the 2006 year. the pros for helical gears are:

- more teeth are in contact with each other at any time, which allows higher loads to be applied or lighter pinion & racks are possible.
-better feedback for the driver;
-maybe also less backslash but that depends on manufacturing

the disadvantage is that with helical gears you create a force in longitudinal direction; the force in longitudinal direction is very undesirable, because it tends to push the rack longitudinal and therefore creating more friction in the system (heavy steering). you can solve this by having two sets of helical gears to cancel out the longitudinal force.

but I doubt whether you want to design it yourself as in 2006 I couldn't find any helical rack and pinion suitable for FS. and the production of gears in genenal is very expensive if you want to make your own one.

cheers Vinnie
05 class 3 Chassis design @ Delft
06 class 1 Steering system design @ Delft
07 class 1 Brake system design @ Delft
08 class 1 Brake system design and possibly tyres @ Oxford Brookes Racing

[TG]

Originally posted by Vinnie:
- more teeth are in contact with each other at any time, which allows higher loads to be applied or lighter pinion & racks are possible.

This depends on the type of failure of the gear teeth which is dependent on the material used and the surface finish. If you are failing due to bending stress, you might find that the thinner teeth of a helical gear may cause the size to increase.

[Vinnie]

<STRIKE>This depends on the type of failure of the gear teeth which is dependent on the material used and the surface finish. If you are failing due to bending stress, you might find that the thinner teeth of a helical gear may cause the size to increase.</STRIKE>

even when bending is the first failure; when having two teeth in contact at the same time, it will divide the force over the two teeth (in stead of one with the normal rack and pinion), which will divide the bending stress on one teeth by 2. and this means that the teeth can be of a smaller size (assuming that you use the same material). this does not account for the pinion itself as the total amount of torque will tay the same.

This is only the case when the helical gears are manufactured with very low tolerances (meaning that both teeth will receive the same amount of force)

cheers vinnie

[Vinnie]

got something mixed up; I wanted to quote you not strikethrough your text, sorry about that

cheers vinnie

[Alicanvettel]

Hello people,

I am new here, i am desinging my univercity's first steering wheel system. I decided to buy rack and pinion. But what would you advice me? We dont have much time . I searched a lot but i just confused more http://fsae.com/groupee_common/emoticons/icon_smile.gif Is the best thing to buy new system? http://fsae.com/groupee_common/emoticons/icon_confused.gif

[Formula Seven]

Originally posted by Alicanvettel:
Hello people,

I am new here, i am desinging my univercity's first steering wheel system. I decided to buy rack and pinion. But what would you advice me? We dont have much time . I searched a lot but i just confused more http://fsae.com/groupee_common/emoticons/icon_smile.gif Is the best thing to buy new system? http://fsae.com/groupee_common/emoticons/icon_confused.gif

Hello,
We produce and sell an helicoidal rack and pinion steering rack. We used helicoidal gears in order to have a smoother engagement and ZERO backlash.
For teams who order our products until March the 31st 2012 and place our sticker on their car there's a 10% discount!

Thanks!