Gear Pressure Angle and Pitch.

[ChrisH]

Originally posted by sanddrag
Matt,
Great photo, thanks for posting it. Where is the planetary? Also, is there a picture that shows what is driving the worm? From what I see near the top right of the picture, it looks as if a chiaphua is driving the worm directly. Also, how is that worm attatched to the shaft it's on, pin keyway?
Very cool.
Thanks.

You can just see the planet gears inside the brass ring on the left side. Now you know why they call it a Ring Gear, the teeth are on the inside. The Worm could have been turned out of the shaft it's on. It kind of looks that way in the picture. In which case there no need for a key or pin. If not I'd guess they used a key as there is no sign of a pin. There is a pin above the worm, but it looks like it is mostly there to hold in the bushing supporting the worm.

[Patrick Wang]

Looking at some of the Specs listed under the Boston Gear's Gear,

the 20 pitch steel 60 tooth gear's torque rating, it says it is 123 in.lbs @ 1200 max RPM.

Could someone explain how a gear like this would work (intuitively and through many people's experiences it should) with one drill motor alone which Stalls at 225 in lbs.

In fact the Chiaphia's 32 pitch gear was more than enough to handle it's stall loads, so why do the numbers seem to deceive here? (Is the rated torque significantly less than the maximum torque available to the gear?)

thanks again all

[Matt Reiland]

Sanddrag,

It is tough to tell from the picture (Plus I don't know what motor they used in this particulat photo) but the motor comes straight down to the worm drive that goes through the hub over to the left and drives a center gear, three brass gears 120 degrees apart are connected to the wheel and the outside brass gear is stationary.

Here is another pic from a slightly different angle, someone from Baxter could probably fill you in but I was impressed enough to take some pictures (Which goes for all of the pictures I post, I have the pictures because I really liked the design)

[sanddrag]

I clearly see a Chiaphua armature fitting itno the internally splined shaft that the worm is on. The worm turns the worm gear and from there I'm lost. Does the large worm gear directly drive the wheel or does it drive the planerty. I see the planetary system but I have no idea what it's for or what it's driving.

[ChrisH]

Originally posted by sanddrag
I clearly see a Chiaphua armature fitting itno the internally splined shaft that the worm is on. The worm turns the worm gear and from there I'm lost. Does the large worm gear directly drive the wheel or does it drive the planerty. I see the planetary system but I have no idea what it's for or what it's driving.

Let me try and rephrase Matt's comment. The worm drives the worm gear. The worm gear is on a common shaft with the sun or center gear of the planetary system. The planet gears are fixed to the wheel. The outer ring gear is fixed to the frame or gear box and does not rotate. The planet gears are meshed with both the sun gear and the ring gear. As the sun gear turns, the planet gears both rotate and move forwards (or backwards, depending on your definition). Since the planet gear shafts are solidly mounted to the wheel, it too must move forward at the same rate as the planet gears. What makes this confusing is that the wheel is mounted on the same shaft as the sum and worm gears, but is not connected to it. The shaft just acts as an axel in this case. A very compact system, but it can be kind of confusing if you're trying to figure it out.

[sanddrag]

Thanks for the help. I completely understand now. Very cool.
Now that that's done with, let's get back to the origional question in this thread. Sorry if I got the thread a little sidetracked but you have to admit that it's a cool design and valuable learning about it.