| Author |
Message |
james stevenson (Jaybee)
Member
Username: Jaybee
Post Number: 1
Registered: 3-2009
| | Posted on Tuesday, March 24, 2009 - 10:01 pm: | 
|
Hi can you supply gear sizes that are not in general stock..??
I have a two stage gearbox 12t to 60t(mod2)then 12t to 50t(mod1.5) with an input of 2600rpm and a wheel size of 500mm,giving a road speed of 7mph.
This is too high so i need to change something,the problem is i can only change the 60t mod2 unless i rip apart the entire machine,
I am going to need a gear of around 90t to make it down to 4.9 mph.
I have found a supplier of gears/racks/shaft etc but there to expensive,(in fact double your prices for regular sizes.)
Can you help.??
Thanks james |
james (Jaybee)
Member
Username: Jaybee
Post Number: 2
Registered: 3-2009
| | Posted on Tuesday, March 24, 2009 - 10:12 pm: |
|
Here is a picture before i fitted everything in for good. |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 1015
Registered: 10-2004
| | Posted on Wednesday, March 25, 2009 - 7:11 am: |
|
James,
As you point out, our Tbot standard MOD gears are relatively low cost compared to other suppliers because we have them made for us in the far east and we buy in large quantities.
We are about to launch a new service of offering non-stocked transmission products. Prices will not be as keen as the Tbot range but we hope they will be still be reasonable. I will check on availability later today and post back here with a price. |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 1016
Registered: 10-2004
| | Posted on Wednesday, March 25, 2009 - 6:49 pm: |
|
James, Once we launch the new service, we will be able to supply MOD 2 90T gears EN8 steel with a boss for £56.15 each incl vat. I checked what HPC sell them for and they come in at £127.84 incl. These are large gears at over 4kg each and 184mm overall diameter. New service should be on-line within 2 weeks or so. |
james (Jaybee)
Member
Username: Jaybee
Post Number: 3
Registered: 3-2009
| | Posted on Wednesday, March 25, 2009 - 9:48 pm: |
|
Thanks, how did you know i looked at HPC..lol
Do you think there is another way around this,
My main concern is that the motors will be running to slow if restricted to 4mph with the current set up and therefor will be low on torque what do you think.?
Hmmm just wondering if i have room to move the motors back and install a 3rd stage with a 12t/20t mod2.!?!?!?! |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 1022
Registered: 10-2004
| | Posted on Thursday, March 26, 2009 - 10:52 am: |
|
James,
If you restrict the motor speed by lowering the voltage then yes, less power also means less torque. As amatter of interest, why have you mixed MOD's?
Unless you can reduce the wheel diameter or accept lower motor power, then you have no choice but to increase the gearing ratio from your 20.83:1 to 31.1 so a third stage is a possible solution.
I trust the chassis is nice and rigid as any flexing will cause a miss-mesh of the gears and that is not a pleasant sound! As the torque is at its lowest at the first stage at the motor end, you could consider belt drive as the extra stage. We only stock T5 timing pulleys and T5 10mm wide belts at the moment but that range is being increased next week. We will have T5 x 25mm and T10 x 16mm. Not sure which size you would need at the moment and it depends on the motor power. Just a thought.
How did I know you looked at HPC, I guessed as they publish their prices on the net, sell to the public and hold an excellent range but they are expensive especially for the hobby market. That is why Technobots is extending its range of transmission products. |
james (Jaybee)
Member
Username: Jaybee
Post Number: 4
Registered: 3-2009
| | Posted on Thursday, March 26, 2009 - 9:57 pm: |
|
I mixed mods because i needed mod2 big enough to fit across the motor but i also wanted the 12t mod1.5 to be fitted inside a 20mm shaft so needed a gear with a smaller section.
A mod2 12t would of meant that the shaft or gear would have to thin for my liking.
 |
james (Jaybee)
Member
Username: Jaybee
Post Number: 5
Registered: 3-2009
| | Posted on Monday, March 30, 2009 - 10:28 pm: |
|
HI, slightly OT but do you think that a tacho feedback system is a better solution.?????? |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 1025
Registered: 10-2004
| | Posted on Wednesday, April 1, 2009 - 7:29 pm: |
|
James,
A tacho feedback system is great where you wish to derate the performance (speed) of an electric drive system but still maintain good torque. Basically the tacho system will apply sufficient voltage to the motor to achieve the desired speed. It works best when you have the correct gearing for the desired top speed. In your case, the gearing is insufficient so to achieve a reduced top speed will still mean a reduced power output. I don't believe you would gain from having a tacho feedback. This is discussed elsewhere on this forum, do a search for tacho 'and' feedback. |
