DIY Electric Car Forums banner
21 - 36 of 36 Posts

·
Registered
Joined
·
2,155 Posts
https://en.wikipedia.org/wiki/Helix_angle#Helical_gear

says nothing about a curve fyi, are you thinking of hypoid? Or are you saying they just drug the involute cutter in a straight line (on an angle to the axis of rotation, i.e. helix), instead of rotating the gear during the cut, and the teeth are deeper in the middle of the gear or something (how would that even work)? I mean we are talking about circles here, there's gonna be a curve somewhere. Did they not use an involute cutter?


also, my own duh, straight cut are definitely louder when loaded, so hard to imagine a healthy straight cut idler making that much racket when the car is in second.

and does OP know the difference between a whine and a screech?!?
 

·
Registered
Joined
·
812 Posts
This is hurting my head to think about this. Name-wise the straight cut gears I'm thinking of are better known as spur gears. piotrsko, I think people are right. The angled teeth need to be in the form of a helix to mesh properly. If the teeth were near perfectly straight, and not in the form of a helix, they would only mesh on the very ends(corners) of the teeth. This would be extremely impractical and undesirable. And, not a design to use in a gearbox.
 

·
Registered
Joined
·
6,477 Posts
https://en.wikipedia.org/wiki/Helix_angle#Helical_gear

says nothing about a curve fyi, are you thinking of hypoid?
No, there are no hypoid gears in this transmission... hypoids are found only a right-angle final drive with the axes of the pinion and ring not intersecting (such as the ring and pinon in the rear axle of this Ranger pickup).

Or are you saying they just drug the involute cutter in a straight line (on an angle to the axis of rotation, i.e. helix), instead of rotating the gear during the cut, and the teeth are deeper in the middle of the gear or something (how would that even work)? I mean we are talking about circles here, there's gonna be a curve somewhere. Did they not use an involute cutter?
Straight-cut teeth are still involute, they just don't spiral like a helical gear. If you cut a section through the gear on a plane perpendicular to the shaft axis, the involute tooth form looks the same whether the gear is straight-cut or helical.

But the TK4's gears (other than reverse) are almost certainly helical anyway...

also, my own duh, straight cut are definitely louder when loaded, so hard to imagine a healthy straight cut idler making that much racket when the car is in second.
Agreed - the reverse is likely straight-cut, but that doesn't matter when it is just idling; straight-cut gears would only be a noise issue for the gear currently in use.
 

·
Registered
Joined
·
6,477 Posts
We are getting somewhat OT here. terrorr, could you address the questions I asked in post 13. Maybe that will get us back on topic.
We're on-topic, in that we're sorting out what piotrsko introduced about "constant-mesh" and "straight-cut" gearing and their relationship to possible gear whine.

I agree that the whole straight-cut thing is likely irrelevant, and that alignment rather than gear whine is a potential issue.
 

·
Registered
Joined
·
6,477 Posts
Name-wise the straight cut gears I'm thinking of are better known as spur gears.
Spur gears are just on parallel shafts - they can be straight-cut or helical. All of the gears in the transmission are spur gears.

The angled teeth need to be in the form of a helix to mesh properly. If the teeth were near perfectly straight, and not in the form of a helix, they would only mesh on the very ends(corners) of the teeth. This would be extremely impractical and undesirable. And, not a design to use in a gearbox.
Actually they mesh just fine whether straight-cut or helical, because they have an involute tooth shape.

Again, unless they are damaged or a shaft is misaligned, the gears in the transmission are not going to be the source of an abnormal noise.
 

·
Registered
Joined
·
2,155 Posts
spur: 1.
a device with a small spike or a spiked wheel that is worn on a rider's heel and used for urging a horse forward.

If we are going to disregard the common vernacular, then even a hypoid pinion gear is a spur gear. But I think it has more to do with how it looks, i.e. from the side, and a helix gear just looks like a circle, not a spur. A straight cut gear looks like a spur, that jingle jangles. First recorded use in 1815-25

But it looks like the brits got confused somewhere, not knowing what cowboys were and whatnot, decided overthink it and make the term more general, instead of asking "hey, what do you mean by 'spur gear'?!?"

http://www.dictionary.com/browse/spur-gear

also worthy of note: http://www.ronsongears.com.au/a-brief-history-of-gears.php
"Various other patents followed until 1897 when Herman Pfauter of Germany invented the first hobbing machine capable of cutting both spur and helical gears."

more than you might want to know about the history of gears:
https://books.google.com/books?id=c...rman Pfauter helical gear patent 1897&f=false
 

·
Registered
Joined
·
812 Posts

·
Registered
Joined
·
6,477 Posts
But it looks like the brits got confused somewhere, not knowing what cowboys were and whatnot, decided overthink it and make the term more general, instead of asking "hey, what do you mean by 'spur gear'?!?
Good catch. :) Usage varies by country...
A British definition:
a gear having involuted teeth either straight or helically cut on a cylindrical surface. Two such gears are used to transmit power between parallel shafts
Anyway, everyone agrees that spur gears rotate on parallel shafts, in contrast to bevel gears.

By the way, they had horses - and riders with spurs - in Britain before any Europeans settled in North America and eventually called themselves "cowboys". The word "spur" itself is apparently from Middle English...

Regardless of what "spur gear" means to anyone, the TK4 is presumably full of helical gears on parallel shafts, and so it shouldn't have excessive gear whine due to straight-cut gears.
 

·
Registered
Joined
·
6,477 Posts
Oh I'm sorry, I just have one and have been inside it to rebuild it. I didn't google it to see how it works, I use the correct ford service manual. How obsolete.

The gears are cut on an angle, there is no helix curve to the cut. Hence my comment straight cut.
That is helical (each tooth is such a small fraction of a turn that it doesn't look curved). So... we're done with talk of gear whine due to straight-cut (or "spur") gears, right?
 

·
Registered
Joined
·
6,477 Posts
... I just have one and have been inside it to rebuild it...
It looks like the TK4 has a common design: a short input shaft has only one gear (to transfer drive to the countershaft), and only a single bearing in the transmission. This would mean that the pilot bearing is required to support the other end for proper gear alignment (not just to align the input shaft and crankshaft). Does this sound correct, from the hands-on perspective?

If the transmission depends on the pilot bearing this way, the kind of coupler or adapter alignment problem which was discussed earlier (post #13 by as electro wrks, as he has reminded us :D) could cause gear noise despite perfectly good (until the misalignment destroys them) helical gears.
 

·
Registered
Joined
·
10 Posts
Re: Max Transmission RPM? Will it blow?

Have you done away with the rubber mounts on the tranny, and do you have rubber mounts on the motor? ANY, solid mounted powertrain component will make a lot of noise, even if it's in perfect order.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #36 ·
Thanks for all the input. Been gone awhile, had to take care of general life issues. The truck is parked for now and I will be working on it again in the spring. After I have more time to test and tinker I will get back with any findings.
 
21 - 36 of 36 Posts
Top