My Design

[Simon Thomas]

Added the safety pin. Vibration and jerking can some time get this part loose. I have learned that vibration and jerking along the travel can push the force upright therefore may loosen the nuts as well.

Safety pin should help preventing this to happen.

 

[Simon Thomas]

I modified my hub disc brake after inspired by jman231994 at http://www.diygokarts.com/vb/showthread.php?t=14373 post #3.

I am more comfortable and confident with this way of attaching my brake disc. I have seen the motorbike has cast ion brake disc holder like the material used in making the bearing housing and this has given me some confidence and comfortability here.

 

[Simon Thomas]

Because of the problem that I am having with my 1st build, I have to modify my 2nd build frame. I have extended the rear frame to put more bearing. I try not to have a broken rear rod anymore.

Because of slight modification here, now I am short of bearing. Need another additional 3 units of same rear bearing. I have called the shop to reserve the same 3 units of bearing for me.

These workes as shown in photos were all done last Saturday.

 

[TeamCheap]

If you run a mild steel solid axle in a high-traction enviroment it will twist and break.

You either need a differential or hardened solid axle.
A differential will work fine in high traction area's but when you get into the rough muddy terrain only one tire will do most of the spinning (usually the one with little traction) or a hardened axle that can take a lot of stress but drive both wheels at the same time.

Or if you can find a locking differential from something like an atv or tractor or small car then you'd be set.A locking differential would allow you to drive most anywhere and when needed you could lock it up and drive both wheels.

Whats breaking the rear axle is the stress from turning and having the inner tire turning in a smaller radius than the outer tire while turning.

 

[Simon Thomas]

Back to my 1st design, I reviewed the weaknesses of the rear axle rod. I found one of the bearing came loose. The screw actually did not hold it tight. Loose in this has caused some bent at weak point.

I believe they arose from the continuous jerking and vibration up and down which eventually broke the axle rod. TeamCheap has good observation on my weaknesses here.

Planned corrective action is something like this (i) add additional unit of bearing (ii) Connect back the broken rod with weld and washer (still not sure how much this can help).

 

[Simon Thomas]

If you run a mild steel solid axle in a high-traction enviroment it will twist and break.

You either need a differential or hardened solid axle.
A differential will work fine in high traction area's but when you get into the rough muddy terrain only one tire will do most of the spinning (usually the one with little traction) or a hardened axle that can take a lot of stress but drive both wheels at the same time.

Or if you can find a locking differential from something like an atv or tractor or small car then you'd be set. A locking differential would allow you to drive most anywhere and when needed you could lock it up and drive both wheels.

Whats breaking the rear axle is the stress from turning and having the inner tire turning in a smaller radius than the outer tire while turning.

Thanks TeamCheap for following-up my thread. I know you can anticipate the problem that I am having now and appreciate your thought. I still have limitation to get the stuffs that you mentioned. Hovewer, I am going to introduce something like this (shown in photo) along the rear axle of my 2nd build. Lorry normally uses this component. I have purchased some parts which I could use to design something like this. May be not as perfect as sold in market because of commercial design, but I hope it is more the less something close to that. Give me time to try this.

For my 1st build, nothing much I can do with it. Just continue with the planned corrective actions since I know the root cause. I wanted to include the "universal joint" component but there is not enough room for it, unless I totally re-design this part from beginning. See whether I need to include universal joint if the problem continues.

The other option to solve my 1st design problem is by using single rear wheel insteas of 2. This has been sugggested by one of our member in earlier post. I am considering this also as part of the solution although this will not provide good grip from the rear wheels especially on the gravel road.

Both 1st and 2nd build will not run at high speed. Probably around 30-40km/hr should be okay.

 

[Simon Thomas]

I bought 3 units of new bearing yesterday together with its screw and washer to hold them on the frame. The same type which I purchased earlier on.

Bearing housing: FBJ brand and Inner Race: brand MZD.

This has booked me to continue my works on 2nd build this weekend again.

 

[Simon Thomas]

I have purchased the bicycle handle as well. I prefer to use the bicycle handle on my 2nd build different from the 1st build which using the car steering. Want to see whether these two types of steering make any different or not.

This will differentiate the setup of my brake and throttle later.

 

[landuse]

Looking good. You are working really fast on your second build. You are soon going to run out of space to store your toys

 

[Simon Thomas]

hahahaha... that is true. This is the big challenge when doing the work at car porch when other stuffs are there at the same time. I only can do my works over the weekend when all the family members prefer to go outside and I could do my work peacefully.

Actually under the canvas are my old motorbike (1 unit), mountain bikes (2 units), small bmx bicycles (3) and motorbike toys (2 units). They are belonged to my nieces and nephews when they spend their weekend with my wife and I. I admit I have to cover these stuffs to prevent them from getting the sparks and dust when welding.

Luckily I still left my 1st build in country side, otherwise I have no space to park my car.

 

[TeamCheap]

I know that sourcing parts is difficult in your location and I am impressed with how you overcome the various obstacles.

I just had a thought and it is really just a few seconds old but here goes.

Maybe you could use a jackshaft and have it drive two belts with each belt driving a seperate rear axle, the belts would act like a slipper clutch when set right.

So you would need two rear axles (your axle cut in half) independant of each other and the belt could allow for a small amount of slippage or you could lever one out so that wheel just coasts until you need the extra traction then engage it.

After seeing your fabrication skills I know that it would be simple for you and only take 6 bearings.
(2 for the jackshaft and 2 each for the axles)
I guess you'd need to double the brakes up though.

Ohh well its just a thought but could be done with basic stuff and eliminate the stress on the axle when turning.

 

[Simon Thomas]

Maybe you could use a jackshaft and have it drive two belts with each belt driving a seperate rear axle, the belts would act like a slipper clutch when set right.

So you would need two rear axles (your axle cut in half) independant of each other and the belt could allow for a small amount of slippage or you could lever one out so that wheel just coasts until you need the extra traction then engage it.

After seeing your fabrication skills I know that it would be simple for you and only take 6 bearings.
(2 for the jackshaft and 2 each for the axles)
I guess you'd need to double the brakes up though.

Ohh well its just a thought but could be done with basic stuff and eliminate the stress on the axle when turning.

Hi TeamCheap,

Thanks for your input. I have been thinking about your suggestions "use a jackshaft and have it drive two belts with each belt driving a seperate rear axle, the belts would act like a slipper clutch when set right". I have attached one photo here and almost similar to your description (correct me if I am wrong).

Your thought are all make sense, practical, good recommendation and suggestion. Speaking of the design in photo, I believe the designer has considered all weaknesses factors until they come out with this rear axle design. From your description, I know you know my problem and in the same time have the knowledge in this area. Appreciate your thought.

However, I have set my strategy to deal with this problem with the frame setup, with the available sources and equipment that I have now. That's my main limit here. Besides, nothing harm to try new method which is being used in the automotive technology. It is not new actually but adopting it here. Let's try this out first.

 

[Simon Thomas]

I am waiting impatiently for tomorrow Saturday so that I could do some works with my 2nd build.

 

[TeamCheap]

There was really nothing wrong with your first design other than using threaded rod and running the cart onto high of traction surfaces and the added stress/leverage from the larger diameter tires your using.
Even our ATV's will strip out the hardened hub and axle splines if we run them on high traction surfaces to much and dont do it correctly.
To do it correctly we have to lean enough on the outside of the turn to lift the inside tire while turning so it can slip otherwise it just wants to push straight and it stress's the driveline.

What I cant see for certain in the picture is if this design has a differential or not but anyway I was thinking of a much simpler and doable design with the supplies I have seen you working with.

Did your first cart ever buck or feel like it was binding up when turning corners, tight corners especially and tend to want to push thru a turn rather than turn tight and easy on high traction surfaces.
(I would think it had to, I have felt it many times on my atv)

From your postings I assume you know how/why a differential works but if you are uncertain there are some great illustrations on the net.

I've seen guys shatter a 1"-1/4 or so drive axle on concrete trucks just from locking the diff and backing out onto pavement and turning.The stuff in those drivelines is pretty tough to be moving 80'000 lbs but can only handle so much stress and will pop if used wrong.

I'm still stuck on you having to much traction and no differential action as the problem.

 

[Simon Thomas]

Hi TeamCheap,

Answer to your question: my first build does not have the diffential at the rear axle. It uses one 1" diameter long straight mild steel shaft connecting the two rear wheels.

I am still working on improving this weaknesses and install it in the 2nd build. I will attach the pictures soon.

 

[Simon Thomas]

I continued my works last weekend Saturday with my 2nd build. As usual put all the parts on car porch floor before deciding the works to be done on that day.

I had decided to solve the rear axle problem with my own design which I adopted from the universal joint mechanism.

I do not know exactly whether this is workable, but I think better give it a try.

 

[Simon Thomas]

I cut the 1" mild steel shaft rod into some portions. 2 portions were used hold the hub. The end was grinded to put the safety pin.

 

[Simon Thomas]

I realized the steering stand was too long. If I need to include the biclycle handle, I need to cut the steering stand a bit.

 

[Simon Thomas]

Fitted the welded left and right rear axle rod together with the wheels. The purpose to see whether they fit properly.

 

[Simon Thomas]

Welded a hollow solid tube at the end of both rear axle rod.