OK you math wiz's

[BuzzStPoint]

The axel rod is 1/2 inch, I have 7 inch wheels.

Changing the wheels is an option, if that would make it easier.. I just need somthing.

If chain and gear is not going to work then I can use a cable and pulley system.

 

[militarymaxx]

Even if you get your setup close, you can always play with the length of the track. I think it would be easier to make the track a few feet shorter (or longer) than to try and find the perfect gear/sled design.

 

[Çh®i§tiªñ]

ok - i see you didnt like the 1:1 car idea.....

how about a catapult?

 

[BuzzStPoint]

for the 1:1 What size gear or pulley system will I need?

The way I see it.

3 inch wheel will roll the sled 9 1/2 inches per 1 Turn
7 inch wheel will roll the sled 22 inches Per 1 turn

The sled will have to roll 360 inches, so.. This is where I get lost..

how big of wheels, How big of pulley or gears.

 

[StaticSag]

I am going in an entire different direction here but can ya give me the distance from the axle centerline to the area where the box sits or the nose of the sled to the axle....you can use pythagorean thereom to figure the correct distance for total distance from sled to axle and save me some time if ya want....you will be better off using a pulley and cable system as to not have to incorporate a gear reduction.

Dont you guys kill me if I'm wrong.....lol...but if you drill a hole thru your 1/2" axle (far left or far right side to keep from rolling over already wrapped cable) and run the cable thru it and attach it so the cable will wind up around the axle the cable will in theory move the box 1.57" per rotation of the 7" tire. I get this from the actual circumfrance of the axle itself. The 7" tire will need to make 16.4 rotations to go the 360" distance. Upon multiplying you get 25.7 foot for the box to move the allotted 30". From my calculations you will need an axle .58" in diameter to move the sled 1.82" per rotation of the 7" tire which will give you a box movement of 29.85" in the 360" track. This is as close as I could get. All you need is a cable that will wind around your axle 17 times from one side to the other and a sleeve on your axle that is .08" thick. This would leave out any gears and pulleys of course but i like to do things the easy way. You know....less maintence with less moveing parts.

Anyways.....LOL if ya want but thats what I came up with.


Saggy

 

[BuzzStPoint]

OK heres what I figured out.

Full pull = 360 inches

Sled
3 inch wheels
	Rotate 9.42 inches per turn
	38.22 turns per 360 inches (Full pull)
Box
1/4 (.25) inch axle
	Rotates .79 inches per turn
	37.97 turns per 30 inches (full sled)

So 3 inch wheels will Turn 38 times every 30 feet, the 1/4 axle will turn 38 times to move the box 30 inches. This will be done by a cable and turning the axel into the pully it self.

are my figures correct?

 

[Krusty]

You're right on the money! Converting feet into inches and then dividing the chain inches into the foot to inch conversion and you will get the correct ratio. You also have to take into account the circumference of the wheels if they are used (we all know how to figure that out, right?), but wheels weren't even part of the original problem as stated, so without that information, it can't be considered at this point. With all the correct info (wheel size and RPM), it will be relatively easy (mathematicly speaking) to work it all out (even the speed) without a model.
Good work MilitaryMaxx!

Originally posted by militarymaxx
Yup, it's all about the ratio. But to throw my .02 cents in, here goes.

If you convert the track length into inches (30' = 360&quot and the sled length is 35", then the ratio would be 35/360 or 10.29:1.
So, for every 10.29" the sled travels down the lane, the weighted box would move 1". So, if my math is at least close, you need to set up your gearing in the 10:1 range. If my math/figuring is completely out to lunch just slap me.

 

[olds97_lss]

Keep in mind, if your winding steel cable around a small shaft it will fatigue in a short while and break. You may be better off figuring out the chain and sprocket method, even though the math is hard to figure without building the sled itself first.

You may also want to build the sled and figure the chain/sprocket after the fact. That way you can get accurate measurements off a completed model.

 

[BuzzStPoint]

thats what I have now. I have the chassis and box/slide made already.

I have not mounted the axles yet. I am waiting till I figure out the system before I mount the rest.

 

[RatzoRC]

2+6%. divided by the.......# X 3.15 - Argh!!!

 

[vbgagnon]

E=MC^2? haha

VB