Project design/motor sizing help needed

[mcfridge]

Hi, I'm new here, but I really need some help on something I am working on. I did a search but couldn't find exactly what I was looking for so I thought I would ask for help:

I am doing a simple design where I use a motor, coupled to a set of gears (probably spur gears), which rotates another shaft, which raises and lowers an amp in the trunk of a car (maybe by means of a screw jack, not quite sure yet). What my question is this: I'm thinking that I have to size the motor first before I can design everything else, but how do I do that? I need the motor to run off 12V DC because I want to run it off the car battery (if possible). I hate asking because I don't want the work done for me, but I needed someone to explain it on kind of a step by step basis (what measurements I need to take, what formulas to use, etc) because I don't have a formal engineering background. Thanks a lot if you can provide any help.

I'll probably cross post this in another forum since I don't know how much people view different forums.

 

[griffengm]

Mac,
Key question: how rapidly? This governs starting torque.
If high speed is not an issue, how about using a window motor or seat lift mechanism?

Griffy

 

[tygerdawg]

You can go to sites for ball screw manufacturers (THK, Nook Industries come to mind) and gearmotor manufacturers (SEW Eurodrive's German site, search "Dokumentation" for their Practical Engineering series of PDF manuals) and get boatloads of catalogs with engineering calculations and "how-to" instructions.

You'll have to do your homework like Griff said, define your parameters: speeds, masses, etc. It may be an iterative task because sometimes torques are dependent upon pulley sizes which are dependent upon torques which are dependent upon pulley sizes which are....

TygerDawg

 

[mcfridge]

Thanks a lot for the help guys.

 

[automatic2]

I would say you spec the motor last. Design the actuating mechanics first, then you can measure the torque and speed you require. That then defines your motor/gearmotor requirements.

 

[carata]

How about a one piece linear actuator from someone like Daneher? I know they are available in 12v
linearactuator.com Good luck.