help to set two gears in motion

I will assume that you know how to assemble and already have assembled the gears so that each has a pin type connection and can freely turn. Next, go into Mechanisms (Applications>Mechanism) and select the icon labelled 'Define gear-pair connections' or from the Mechanism menu at the top, select Gears. On the gear definition manager, press the 'New' button will open the 'Gear Pair Definition' input screen where you can name the gear pair, select whether it will be standard type driver/driven pair or rack and pinion, select the joint axis of whatever gears will rotate and give it some numbers for pitch diameter and number of teeth for each gear. The first gear you pick will be the 'carrier', the second will be the 'gear'. When you selected and defined Gear1, click the Gear2 tab and define the second gear. Pick a place to put the gear pair icon, click Okay and you're done. Give one of them a motor, set up the Motion definition and you're off and running.

BTW, this functionality started fairly recently, possibly even with Wildfire. I'm not sure what you'll do if you have an older version of the software and there is not gear pair connection available. You could possibly put a motor on each and use both motors in your motion definiton, never tried it.

David Janes

David,

Thanks for the reply. very valuable information, unfortunately I haven't been able to find the mechanism you have mentioned, I am afraid my version of Pro-E doesn't have it, or has been restricted form the licence, I am using Pro-E 2001 educational version.

I already have the gears spinning freely, but I haven't find the way to link them at the diameter pitch, and putting a motor on each and use both motors in motion definiton will be useful to show a motion, but I need it to set an epicyclic gearbox to analyse the output speed in the arm and the rig, so I am afraid I need to add a motor on only one gear and the other should move as a consequence of the movement of the first one.

However, I appreciate your help, and in case you have any additional comment, I will be really grateful

Ulises

PS. What version are you using at the moment?

: I already have the gears spinning freely, but I haven't find the way to link : them at the diameter pitch, and putting a motor on each and use : both motors in motion definiton will be useful to show a motion, but I need : it to set an epicyclic gearbox to analyse the output speed in the arm and : the rig, so I am afraid I need to add a motor on only one gear and the other : should move as a consequence of the movement of the first one. : I'm sorry I can't help you with this. I've seen quite a few gear boxes but never one that could be described as epicyclic, even those with complicated planetary gear systems. The motor control might be epicyclic, but not the gear box. Are you talking about a motor control, a motion defintion?

David Janes

yes I was talking about motion definition (wonder if I am right) to set for one of the gears. The epiciclyc geaxbox I am trying to model is actually a complicated planetary gear system (wonder if it is because it is UK), that needs two speed inputs to obtain one output (2 degree of freedom system ), and that I agree is quite complex.

So, I will continue looking for a way to do it, and if I find anyway, I'll let you know...

cheers

Hi there, could you please explain me how to set a gear freely in motion with pin locator. Thanks in advance

One of the nice things about gears is that when a tooth moves in the driver, another tooth moves exactly the same amount in the driven gear, one tooth in each. The proportionality is decided by a simple ratio, even if it's something like 17 teeth in the driver to 79 teeth in the driven gear (17/79). One full turn of the driver will produce a proportional motion in the driven governed by this ratio, or

17:79 in the driven.

This ratio then governs all the equations of motion used by Mechanism Design in Pro/e. I'm not sure where, but there is a place in the epicyclic equation where these values can be inserted for the driven gear to give you proportional motion. So, in a time dependent system, the driver will be 17t/s. The driven will be

17:79t/s in a separate driver for the driven gear. In effect, they will appear to move together, yet they will be separately driven, but in proportion to their ratio. Both 'motors' will be used in the new analysis you run. If they both start and stop at the same time, the driver will appear to be moving the driven gear. Yes, it will be an illusion, but that's computers for you. And the result will be the same. Loading, dampers and that kind of thing may not be possible when you have not defined contact between teeth. The problem with defining this is that the contact is intermittent. However, with starting conditions set properly, you should be able to get the gears moving so that good involute tooth profile produces no interference with interference checking set. With compound gearing and idlers, you must do the gear pairs manually, based on the intial ratio.

David Janes

"Shankar Venkateswaran" wrote in message news: snipped-for-privacy@posting.google.com... : Hi there, could you please explain me how to set a gear freely in : motion with pin locator.

The problem everyone has is that they expect to be able to create mechisms with 'Applications>Mechanism'. No, the problem of making components in an asssembly 'moveable' was thought to be best approached in assembly. This is the function of that little bar with the arrow above the usual constraints box called 'Connections'. If you click the arrow, you get a whole interface. In this interface, you start with a base which is not moveable (for example, assembly datums and axes for gear centers), then add components which are, in various ways, with various DOF, moveable. Each connection type has different dofs. The pin type connection allows complete freedom of movement around an axis but constraint in a plane normal to the axis of movement. When each gear is thus contrained, it can move freely about this axis. Then you go into 'Application>Mechanism'. At this point, you have two gears, with packaged type constraints, i.e. moveable in at least one DOF. The Mechanism menu gives you the ability to define 'motors' (a movement defintion, such as a simple velocity or acceleration, continuing for a certain duration.) At each increment of movement, a picture is taken, a snapshot, which can be recorded with 'Capture' and turned into an MPEG file. The sequence of movement may be run with interference detection so that any contact between bodies will be recorded in red. A most wonderful tool!!

David Janes

A couple of years ago I modeled some gears and actually had them run together with a 'cam' definition that allowed liftoff, by setting the entire surface of each gear as the cam.

Very compute intensive, but it worked. Your gears need to be modelled accurately, and the liftoff takes care of the relief at the bottom of the tooth, as well as backlash.

Regards Pete

David Janes

Made this work last night in 2001. I modelled 2 spur gears, 20t, 20p. Made 2 pins, assembled them at center distance (1.00), and pin connnected the gears to them. Went into mechanism>model>cams and defined the gear tooth surfaces of gear 1 as a cam 1, and the gear tooth surfaces of gear 2 as cam 2, and enabled liftoff. Put a motor on the joint axis of gear 1, and off they went.

Pete

Your way, aside from computing horsepower needed, at least offers the possibility, with contact surfaces and real tooth geometry, of loading them, doing interference studies, stress analysis and realistic speed, torque and other behavior curves at the end of the drive train. Thanks and I hope Ulises Diego is getting this.

David Janes

Did you receive the mpeg file?

Yeah, thanks, very cool stuff. Are those gears the product of a gear design program? I saw something for Pro/e from AGMA a few years ago and wish I'd kept it.

David Janes

Nah, made those myself a few years ago. Wish I'd known about the templates and techniques available, because I used sketcher relations to actually draw the involute, and then pattern it around; it's a real beast. But very accurate, I've even double-checked my over pin dims from my Excel program (that I also wrote) by sketching tangent circles and measuring them. Doesn't account for thinning, though.

Regards

: Doesn't account for thinning, though. : Just throw some lapping compound on them. They'll wear in in a couple days.

Try the gears designed on the following link.

Doug

David Janes

Hi

I am now trying to model the gears following

to try the cam-follower, but for some reason I can't see any picture, any of you happen to have the pictures? to draw the gear in the easiest possible way

many thanks in advance

Ulises