18 replies to this topic

[48 Pitch]

Is this for real!... I didn't know they ever used bevel cut gears on slot cars, even in the early days.


 
I got this motor a few years ago from a friend and just figured maybe someone had used it for something other than a slot car and had a bevel pinion on it, but now I dont know.

If its true then did they maybe even use helical cut beveled gears also?

I know its a strange question but Ill explain in another post.
 
Jeff

[A. J. Hoyt]

I always understood that helical cut gears were used to add some "meat" to the base and length to the sliding area for strength and were in favor because it reduced noise. The tend to create some axial thrust, also.
 
If plastic crowns are used, most of the "rules" are out the window. Also, none of that matters at this scale because the torque isn't high enough to shear a tooth and the plastic will just conform/break in to whatever you throw at it (within reason). It's all even less important for HO scale stuff - simply amazing, from an engineering standpoint, what combinations work well!
 
This tapered pinion looks about right with the outer tip of the tooth wider at the narrow cone end of the bevel. It also looks really old.
 
This is my way underinformed opinion.
 
Keep it in the slot,
 
AJ

[Gator Bob]

"Lubriplate" 
 

If it’s true then did they maybe even use helical cut beveled gears also?

 
I have never seen beveled slot gears cut as helical for hypoid use. 
 
That... um... I remember.... LOL.
 
They sound nice.
 

I always understood that helical cut gears were used to add some "meat" to the base and length to the sliding area for strength and were in favor because it reduced noise.

 
And... offset the pinion/axle centerline. Lower driveshaft tunnel... LOL.

[Cheater]

Jeff,

Bevel gears were actually quite common in the '60s. Here's some examples courtesy of eBay:







To the best of my knowledge, helical gears were never used in slot racing, which makes sense as their advantages are not important in slot cars:

Advantages of the helical gear:

1) Silent operation: In a helical gear train, the teeth engage a little at a time rather than the entire face at once. This causes less noisy power transfer in case of helical gears.
2) Non-parallel shaft: Helical gears can be used for transferring power between non-parallel shafts. Though you have to compromise on efficiency in this case.
3) Strength: For same tooth size (module) and equivalent width, helical gears can handle more load than spur gears because the helical gear tooth is effectively larger since it is diagonally positioned.

As to why bevel gears are not used today, I have to guess. I think the essential reasons are cost of manufacture combined with the fact that simpler gear tooth forms actually work as well or even better in slot cars. Plus helical gears seem to require metal material, which makes them much heavier than plastic gears.

[Cheater]

It's perhaps worth mentioning that hypoid gears are a variation of a spiral bevel gear set in which the pinion axis is below the ring gear axis instead of intersecting it.

Thus all hypoid gears are helical but not all helical gears are hypoid.

[don.siegel]

Bevel gears were the favorites for inline slot cars from the time they first came out, probably by MRRC in about 1959, until the plastic gears by Cox began to take over in 1965...
 
They were much smoother than the cheaper stamped gears available on the early slot car kits, or the rough die cast gears made by MDC, Dynamic, etc. - but still had to be run in, and were a little fiddly to set up right. Once set up right, they would run forever (of course, the earlier motors didn't have quite the speed of later jobs...)
 
There were hypoid bevel gears by a couple companies (Strombecker if I remember right...), but I don't think that's the same thing as a helical gear...
 
Now, again if I remember right, the Faller 1/24 cars from Germany had helical spur gears - will try to post a picture later, or take a look in eBay Germany...
 
Don

[Lone Wolf]

Jeff, with a user name like 48 Pitch I would have thought you knew all about gears. 

 

Anyway, bevels were offered in standard and hypoid versions.

 

Gear set on top is standard with straight teeth and a very angled pinion. The lower set is hypoid as you can see by the angled teeth. Also notice the much less severe angle on the pinion.

 

The motor you show is a sidewinder type and would not use bevels although anything was possible in the mind of thirteen-year-olds back then. 

 

[Jairus]

I like them!

 

[48 Pitch]

Thanks guys!... Some great information from everyone.
 
It’s true, I’m not the gear head my user name would imply. But with all your help I’m learning about gears fast.  
 
I was at the salvage yard on Saturday getting a couple of heatsinks for my controller project. While I was there I happened to see some bins full of gears that looked a lot like '60s slot car gears. I headed back there today and here is what I came back with for $11.48.
 

 
That all look new, no sign of use.
 
[So would those two brass gears in the one picture be considered hypoid and not helical?
 

 
They still have the little straight blade set screws in them also.

I’m gonna have to do a scratchbuilt '60s train motor car now.

I tried to get a varity of what they had there but there is still some examples I didn’t get.
Lots of aluminum and brass spur gears, some look like they thread on to the axle and others just have a hole so I’m not sure how they fasten to the axle.

I didn’t see any shallower angle pinions for the hypoid setups but the three pinions I got are pretty close to a right angle when you have the pinion setting all the way down making contact full width.

So do you guys think these are all slot car gears?
 
Jeff

[slotbaker]

Bruce Patto has three sets listed on his Gears and Bearings page at $5 each.

[Gator Bob]

It's perhaps worth mentioning that hypoid gears are a variation of a spiral bevel gear set in which the pinion axis is below the ring gear axis instead of intersecting it.

Thus all hypoid gears are helical but not all helical gears are hypoid.

Or become/break in to... with help from a cigar lighter or heat gun.
 

It’s true, I’m not the gear head my user name would imply.

Joe used my first choice 48 pitch line ...
Is that the speed of the ball when you throw?
 

So would those two brass gears in the one picture be considered hypoid and not helical?

 

They are beveled, hypoid, and the face gear (crown or ring) is helical. Pinion is straight cut beveled... they are not a spiral bevel set.
 

I didn’t see any shallower angle pinions for the hypoid setups but the three pinions I got are pretty close to a right angle when you have the pinion setting all the way down making contact full width.

That would be the match.
 

So do you guys think these are all slot car gears?

 

Yes.

[don.siegel]

Here are the gears on a Faller 1/24 car, which are believe are helical, but in a spur gear setup. 

 

[Gator Bob]

Yes, typical helical cut gear set as used in automotive and industrial apps.

 

Higher end gears on an older slot. Very nice!

 

The good:

High torque load

quieter running

long wear

 

The bad:

More friction

high thrust force

[Dennis David]

Typical German over-engineering, you gotta love it.

[48 Pitch]

Looks like the slot car manufactures tried every gear configuration they could think of at one time or another.

[don.siegel]

Typical German over-engineering, you gotta love it.

 
Yep, while I'm not in favor of national stereotypes, this seems to apply to many German slot cars... what's funny from the land of Mercedes and Auto Union is that a lot of them at the time were fairly slow! (including those multiple gear trains on the Marklin cars - how strange in a 1/32 model, but Marx did that, too)
 
And yes, pretty much every gear configuration was tried, from none to many, from worm to crown to spur... 
 
Don

[Gator Bob]

That helical steel spur looks great.... if in an oil bath ... probably could run for a hundred years.

 

The cut of the gear and the resulting thrust costs a bit of HP but is offset by the 'smoothness' from the thrust pressure.

 

It takes up "The Slack" in the end-play of the motor and axle shafts AND the consistent tooth face contact engagement pattern.

 

With a balanced arm and BB's all around (super premium BBs on the thrust side) ... Shhh .. can you hear it   

[Phloidboy1]

Ref; "THE THING"  Altered /lightened Ram DC857 3V motor, balanced epoxied arm, neoz magnet, in-line drive, Rod body, has too much horsepower & tearing up conventional crown gears, so trying to go to bevel gears, but,

Seems like K&B #506 Bevel gear 18 tooth Pinion does not mate with Tradeship #318 Bevel gear 66 tooth,  which would be a nice 3.67:1 ratio.. what the heck, why isn't the pressure angle the same & or why is it not indicated on bevel gear packaging? 

Anybody know what these pressure angles are?

Or recommend  stronger crown gears, RC gears ok too, 1/8/ shafts set screws, 48 pitch or,  approx 3.5 to 3.75:1 ratio

What an inconvenience!

[Dave Crevie]

Bevel gears are normally sold in sets. The cost of manufacturing caused them to disappear from slot racing, but model railroaders have continued to use them. Considering that the Cox/Parma style crown gears are so cheap to produce, they have become the primary style offered. Bevel pinions work pretty well with them, so there hasn't been a big need for matched bevel sets. The fact that slot racing basically left in-line type chassis behind, helped make bevel gears unnecessary.