If you are updated about my designs you will know i have recently published MyRCCar 1/10 Monster / Crawler Chassis. This chassis design has a very high center of gravity, compared to my previous plain chassis, so its not appropriate for high speeds.
On the other hand, the combination of Motor/ESC and transmission was not the best for extra slow speeds because the motor was getting sooo hot sooo quick.
That's when i thought: "Hey, those commercial crawlers use very big reduction gearboxes, and those i know who crawl tell me about their crawler max speed is little more than a human walking"
Then I thought about my Lego and my geared bycicle, something like "if i reduce speed 4 times, maybe i have 4 times more strength"... Obviously this is a simplyfied version of reality, but the main idea seems to have worked great!!!
And what extra hardware is needed? Just four 10x15x4 bearings and two M3x10 screws.
The "gearing" thing goes like this:
- The motor has a 14T pinion wich attacks a 28T spur. This is the first 1:2 reduction
- Previous Spur shares axle with 14T printed pinion wich attacks another 28T Spur. This is the second 1:2 reduction
- Previous Spur shares axle with the 14T pinion wich attacks the 44T Center Diff. This is another 1:3.14 reduction
-The center diff shares axle with F/R diff pinions, wich are 13T and attack the F/R diffs wich i think are 38T. This makes the final 1:2.92 reduction.
So what is the total reduction ratio for the transmission?¿? 1/2 X 1/2 X 1/3.14 X 1/2.92
Using the Trooper Dif, a 14T motor pinion and the provided gear box the total gearing ratio is aprox 1:37
So after the change, the rc car sounds "horrible" like the crawlers of all those videos i have seen to get documented.
What more has changed?¿?
- The motor now max temp is under 40ºC after long play instead of 90ºC after 5min
- Due to the great gearing, the car doesn't go forwards/backwards easily when in a ramp
- You can give full throttle or max brake instantly apparently without breaking nothing
- You have a very bigger range in your throttle to play with in extra low speeds
- The torque is awesome! I'm sure you could climb a lot of inclination degrees with blocked diffs
I have not intensively played with it already but i will in the next weeks so, if there is something going wrong i will tell you here, and if i can i'll make the necessary modifications to make it work better.
NEW: This Yuran Liu's Video of MTC Chassis with 1:3 gearbox is the best one by now...Take a look also to the MyRCCar MTC Chassis with the Typical Pickup Body in Action! In this video I'm using a 1:3 reduction gearbox too. Everything went ok but, after doing the video i gave some hard accel / braking and some teeth of my ABS pinion wich attacks the center diff broke... I will give a try to the 1:2 version someday!
I have also replaced the MRCC_MTC_Cover_TopCenter, MRCC_MTC_Platform_Central and MRCC_MTC_CD_TOP parts in the MTC Chassis publication, so re-download it to have the right set of parts so you dont have to re-print them to use the gearbox, you should just have to print the gearbox body.