Need help on irreversible screw drive system

[aerosandy]

Hello,

I am trying to design an irreversible actuator system for trim assembly in small jets. I'am having problems with the present ACME threads, for linear motion. So we are designing it with a thread system with 4 leads. When I say 4 leads, its got 4 different threads starting on the same shaft, this increases the pitch on each threads and also makes the system irreversible (hope everyone can visualise this!). This drive system actually works real good, when compared to the ACME thread system.

My question here is, does anyone here know more about the vendors for these kind of screw drive system or actuator system. Coz am not able to get any search for these kind of threads. And also is there a place on the web where I can get more details about different screw drive system. (Hope this is the right forum for this kind of help!!)

Thanks,

Sandy

 

[Metalguy]

Way back in 1960 I worked at the Walter Kidde Co. Among other things they made ballscrew actuators for the afterburner "irises" for some jet engines-not J57's, IIRC).

Dunno if they still make them, but they worked pretty well at 900 deg. F.

 

[thruthefence]

I'm pretty sure the flight control trim actuators on the 500 series Cessna Citations have this arrangement on the jack screws

 

[Fabrico]

That's called a multi lead screw or multi lead thread. They are all over the place, you just don't know it. Take a look at your typical plastic milk jug, soft drink bottle, or some toothpast tubes.

Don't know of a supply but anyone that can make acme threads on a lathe can give you almost any number of leads you want. It is only limited by thread size vs work piece diameter.

 

[aerosandy]

Hello all,
Thanks a lot for all your advice, i had a question for thruthefence's suggestion , I had a chance to check out the Cessna 500 trim actuator system. And it really works perfect for our application. But is there any place I can get more details on their system, like vednors, specs for the Cessna manual trim actuator system. Or any other details.

Thanks in advance.

 

[thruthefence]

The actuators are a "Cessna mfg" part, and as such are included in the Citation Component Maintenance Manual. This is published as a seperate document from the Normal Maintenance Manual, or the vendor maintenance documents, such as wheels or brakes. Any shop who works on Cessna Citations should have access to them. Maybe even a set of outdated "reference only " fiche or CD's. Remember, a case of beer is the currency of choice for us maintenance types, especially late on a friday afternoon.

 

[Ataloss]

If you're just looking for the multi-lead "threaded rod" and not a finished system, McMaster Carr has a selection of rods and various nuts you can use to fab up whatever you need. Just search for 'acme lead screw' at

http://www.mcmaster.com.

They have many different sizes and number of leads.

Bob