Thoughts on next RC blower


Author: Dave
Date: 07.06.18 - 12:29am



So I am starting to play with some ideas for the next RC snowblower. I will start with a video:



The new tracks you see are off of an 1994? era MTD 314-642F000
  • ground contact length: 9.25in, 5in drive height (center wheel)
  • 4.5w, 19"L x 9.25"H
  • drive wheels 7.5in diameter, 10 tooth, 2in lug width, 3/4 radius, rim 5/8in thick
  • track: 2-3/8 in spacing on lugs 3/4in height, 13/16 gap
I like the deep lugs but I just realized these are actually sorter than my current ones. The Craftsman ones i used are
  • ground contact length: 12.5in, 6.5in drive height (offset with chain)
  • 5.5w, 21.5"L x 9.5"H
If i could find another set of these new tracks I could use two per side to lengthen the ground contact surface to 19" total per side. The rubber tracks seems to go for 45 used and the wheels are like 60 each :-

So that would be another 330 if buying from individual pieces and if you could even find them. 200 for the drive unit I got is feeling better all the time.

I can see a solution where one is inside and one outside the frame with a pillow block and single axel and sprocket per side. not a horrible solution if I had the parts on hand or found cheap but the wheel size has to be exactly the same as the unit I already have. then I would probably be in about 600 (with delivery) for the complete set of tracks and wheels. Not horrible but again the parts are from the mid 90's. Rubber is cracking here. Tracks are expensive, but I might be able to do better with a little more cheddar.

Several people have mentioned Toro Dingo tracks. On ebay and amazon looks like you can find a 6in wide track for $200-300.



If you want an interesting read check out the Dingo service manual with lots of picts on how they designed their machine

Studying the designs from service manuals can reveal lots of cool insights if you take the time. Its like looking over an engineering teams shoulder once you can read into the unspoken design decisions they committed to in their product.

The tracks are reasonable priced but the drive and idler wheels are not. I mean probably not that hard to fabricate accurately but I only have a small rotary table and small 9in lathe. Actually it looks like its drive wheels are two rings with rod spokes welded across which both drives and aligns the track/ keeps it from sliding off all in one shot. (plus all the boogie wheels down the length to align and bear load).

Not sure I had seen that design yet. I still dont know the tracks exact dimensions or lug pitch yet :-

This would be a fairly easy and forgiving design to replicate in a small home shop but would be time intensive.

Still maybe we can do better labor/cost wise. So I kept searching and ran across made-in-china.com. Searches for one of the interesting part numbers lead me directly to a manufactures site, pytracks.com

So I reached out to one of the manufacturers of complete track systems. They will sell to individuals in the USA and ship direct from china. She mailed me their Small Rubber Track System Catalog

Looks like they are made to suit with a production time of 15 days and need to confirm tech drawings. Awesome.



The current price for a pair of LXH-148 is $750 + $680 FEDEX shipping. Delivery time is 6-78 days though :-( see order timeline at end :)

Still this is pretty reasonable even with the insane shipping costs.

Sooo..humm. I can currently buy a set of used atv tracks on craigslist local for 2500. Thats $625 each and I can have them tomorrow. I will have to modify them though. The front tracks have lead in and lead out angles I dont want. They are like 12in wide and have to be narrowed, however it looks like I can cut down to 6in wide as all drive and alignment is in center of track only.

They might literally be to long for my project (need to center weight) but I could extend upward and narrow base. Also I will have to over invest by 1200 and wait till I have another project that takes two more or sell the other two off. (The rear two are flat and wont need as much modifying I think)

OR since these hydro untis are already oversized I could just up the level of bad assery and make something that I ride like a skid steer or all terrain wheel chair and use that 4ft wide blower I have in storage.

Damn it. Time will tell. time will tell. And the parts I have will tell me to. Will see which way the wind blows :)

Here are a couple videos exploring the hydro units from the zero turn mower I picked up cheap. Here I explore their design, analyze inputs and outputs, forces, and test controlling it with a RC servo. I also found the hydro-gear service manual for these.







Updates:
  • july 17 I just ordered a set of the tracks!
  • aug 8th received pictures of completed tracks - waiting on shipping number
  • shipped aug 18th
  • received aug 22nd




So a couple more thoughts on the tracks and hydro transmissions.

  • one revolution of track cog = 32" of linear travel
  • hydro trans max rpm = 3000 according to manual, so at max speed 120 output rpm
  • this gives us 3.6mph top speed if direct drive (no gearing with sprockets)
  • original minizoom mower top speed was 6.4mph with 17in tires.


The 3/4in output shaft on the hydros looks small compared to the tracks but the machine weight will be within their ratings. Plot twist the hubs on the hydros are splined not keyed and I havent been able to get them off yet with quite a bit of force. I can not replicate the splines, so would have to use or modify the existing hub..which means I can not damage it getting either piece getting it off. Hubs are not available for purchase for this hydro unit anymore and I am not taking it apart. Also the hydro units while nice and self contained are an awkward size and have almost no flat surfaces. Trying to Mocking the pieces up in hold them in place sucks.

Trying to directly mate the hydros to the existing mounting flanges on the tracks will not be space efficient. Probably have to modify hubs on tracks instead of just a simple adapter plate. Maybe convert to 1in keyed output shaft and an inboard pillow block bearing with a sprocket and chain drive to the hydro.

I could potentially sell them for $250 a piece which is a good chunk towards building a hydraulic system from the ground up with my own spec'd pump, hydraulic motors and proportional valve which would be much more regular shapes and I can define (or screw up) all the specs to my choosing. Also who knows how long it would take for the hydros to sell, and I would have to find new valve plates for the ones I modified for the servos.

Which way to go which way to go. Honestly I enjoy this part, mind swimming in possibilities, but it is taxing at the same time.










Comments: (1)

On 08.17.18 - 10:57am Dave wrote:
just found a $100 riding mower with bad deck. 14.5hp commercial briggs engine runs great. Will also part out mower and try to recoup the initial investment.

 
Leave Comment:
Name:
Email: (not shown)
Message: (Required)
Math Question: 4 + 11 = ? followed by the letter: N 



About Me
More Blogs
Main Site
Posts:
Electronic dividing head
Thoughts on next RC blower
Crawl Space Forklift
Remote Control Snowblower
Servo control for linear actuator
Arduino RC motor control
Keyboard Emulation
Arduino w/ win2k
Arduino Snowblower chute control
Attic Fan Remote Control
Robotic Arm
ATTiny Watchdog
ESP-LINK Huzzah
IoT Humidor v2
Arduino Bugs
Arduino INI library
Arduino Yun
long watchdog
Arduino runtime config
CNC Rotary table
AutoWater humidifier
Humidor AutoWater
KeyPad Bruteforcer