R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Thread Tools Search this Thread
Old 11-07-2009, 03:28 PM   #1
Tech Initiate
RR826's Avatar
Join Date: Oct 2009
Location: N.y,The Bronx
Posts: 42
Send a message via AIM to RR826
Questions?? Helical gears???????

Has anyone ever heard of using helical gears for rc cars like the tc3??????I read they are stronger,more quiet,and have more contact.
RR826 is offline   Reply With Quote
Old 11-07-2009, 04:49 PM   #2
Tech Elite
tom_chang79's Avatar
Join Date: Jul 2008
Location: Southern California
Posts: 2,591
Trader Rating: 13 (100%+)

TC3 doesn't use the helical gears if I remember correctly (the BJ4WE I used to have used TC3 transmissions).

Do you mean the crown and bevel spur gear setup? I thought all shaft-driven 4wd uses this scheme (even in off-road).

Helical gears, to my knowledge, is the gear type that is used on the Tamiya 801x Nitro.

Where it's similar to the TC3's crown and bevel, but instead of the teeth being straight, it is curved...

I don't have an 801 pic for you but this is what I'm talking about:

The gears are just like crown and bevel, but they are curved, since it's "HELICal"

I believe mechanically, this forces efficiency only in one direction...
tom_chang79 is offline   Reply With Quote
Old 11-07-2009, 06:30 PM   #3
Tech Apprentice
Join Date: Sep 2006
Location: uk
Posts: 59

Hey... I think he's asking if he knows of anyone who has tried to use helical gears in a tc3 - not stating that the tc3 uses them
monstercol is offline   Reply With Quote
Old 11-07-2009, 08:40 PM   #4
Tech Master
Join Date: Nov 2003
Posts: 1,850
Trader Rating: 5 (100%+)

They are used in some 1/8th offroad buggies. The only 1/10th 4wd electric that I know of that used helical cut gears in the front and rear gearbox was the old Tenth Technology Predator series. Dunno if they still do or not. Not really worth it, IMO. Molding/machining the gears would cost a good bit more, and the increased surface contact of each tooth actually creates more friction and more drivetrain loss. Probably not worth it for a bit smoother drivertrain and a little more strength in the teeth. Probably be less tolerant to gear lash adjustments too, compared to straight cut gears.
Serpent SRX8 electric
Serpent Cobra 811TE-E
Serpent S120LTR 17.5 1/12th and S100LTR Pro-10
Serpent S411 Eryx 4.0 USGT
Team Serpent America and Desoto Racing
Stealth_RT is offline   Reply With Quote
Old 11-09-2009, 11:25 AM   #5
Tech Initiate
RR826's Avatar
Join Date: Oct 2009
Location: N.y,The Bronx
Posts: 42
Send a message via AIM to RR826

I did mean helical gears to replace the spur and pinion gear......would it really cost a noticeable amount of friction increase and decrease in drive train power?I was looking at my tc3s 72T spur & it looks chewed up a little.Im trying a new set up and want a smooth drive.Maybe it will help with decreasing motor vibration as well,smooth pinion action smooth armature revs.Idk im just asking.
RR826 is offline   Reply With Quote
Old 11-09-2009, 01:06 PM   #6
Tech Fanatic
Join Date: Jun 2005
Posts: 900

Helical gears for the spur and pinion would require the use of thrust races in the system, adding to cost, weight and drag. When a straight-cut gear is in operation, the resultant force drives the gears apart against the bearings already in use in the motor and drive shaft.

When a helical gear is under load, the resultant force drives the gears apart in a side load/motion that would push the driveshaft against the drive cups. Some sort of thrust race would be needed to prevent it jamming into one end. Same for the motor, the helical will push/pull the armature/rotor to one end of the motor putting end loads on a bearing designed for radial loads.

A double helical spur/pinion would contain those forces and prevent side loads, but that's a complex thing to design and mould accurately.

If helical gears were used in the gearboxes (as bevel gears) then because the tooth contact is greater, the gears could be smaller. Smaller gears would reduce the drag. It's all about tooth loading. The more teeth in contact during power transfer, the smaller the contact area of each tooth needs to be. Helical bevel gears are used in applications where size is important (as they can be smaller than straight-cut) or where noise is an issue (because they are quieter).

Hypoid bevels are used where height is an issue, as the pinion can run a centreline below the centreline of the crownwheel. Hypoid bevels are usually used in automotive applications.

All in all, the straight-cut design is more than adequate to deal with RC loads, and we are not usually worried by noise or driveline height. That helical gears can be more efficient than their straight-cut equivalents is well proven, but the cost and complication for RC just isn't worth the effort. HTH
SlowerOne is offline   Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
1/10 Formula 1 Car Forums kuanseng1981 Singapore R/C Racers 4449 07-24-2015 11:28 PM
Helical vs. straight cut diff gears???..... ganymede Nitro Off-Road 48 05-29-2011 09:18 AM
New Caster Racing Nitro Buggy Just Announced! hakmazter Nitro Off-Road 534 07-31-2010 06:20 PM
Faster? Belt-Shaft Losifreak Electric On-Road 69 08-30-2004 10:06 AM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 02:14 AM.

Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net

SEO by vBSEO 3.5.0