Homemade 6x6 with 3 cylinder motor

[rodp]

Chris, Kelvin's an Aussie mate, they don't do things by numbers, they just build them and go "There ya go Sheila, that's a beaut" ..........................And it usually works

[kelvin]

rodp you hit the nail right on the head their thats pritty much exactly how it work over hear i try and do some math and workings out say for like the total volume of the hull. Chris i will try get a manual but if not i will cound the motor revolutions of the pully and final drive

[rodp]

rodp you hit the nail right on the head their thats pritty much exactly how it work over hear i try and do some math and workings out say for like the total volume of the hull. Chris i will try get a manual but if not i will cound the motor revolutions of the pully and final drive

Nothing wrong with that way of doing things mate, it's still the way most hobbyists and small businesses do things over here. Like you, we do try and do some technical stuff but at the end of the day if it works then that's sound. Also like you, we don't seem to have the disposable income that folk in the USA have so we make do and mend.

[kelvin]

this is what i got up to today

[kelvin]

chris first gear is 3/1 and dif is 4.5/1 and still working on tourqe. so whould the total ratio be 7.5/1 plus the chain ratio of 4/1 so 11.5/1 or is that compleatly wrong?

[chris davison]

Hi Kelvin lets do a hypothetical situation say your motor puts out 50 ftp at 1000 rpm then you plug in your first # 3:1 ratio now you put out 333.33 rpm at 150 fpt now plug in your next ratio of 4.5 and you have 74.07 rpm at 675 fpt then your last 4:1 ratio= 18.51 rpm at 2700 fpt so in this situation at 1000 rpm in first gear your axles are going 18.51 rpm with 2700 fpt avail. any time you cut your rpm with gear reduction you increase the torq by the same ratio. My question to you is what size chains are you using?

[kelvin]

ok so engine tourqe is 55.7 at 3200 rpm by my calculations thats about 3000 foot pounds of tourqe and i think thats about similer to your engine chris if mine was doing 2600rpm. And also chris i am using 3/4 or #60 american chain as its heavier than british my drive sprockets on each axle ar 20 tooth and 30 on the main drive axle the axles are 1"3/8 tyres ar 30" diameter

[chris davison]

Cool now you have an idea what it will do #60 chain is kind of small but you should be ok for a while. working strength is only 1036 lbs. double wide 60 would be perfect its around 3400 lbs. With those tires thats about 5.28 mph in first at 3200 rpm

[kelvin]

i worked out that if i stalled the 6x6 in first their would be about 4 tone of weight in total so 2 tone each side but that isnt very likly to happen

[chris davison]

You would break a chain first.

[kelvin]

deffinatly but thats if i get 100% traction and if the thing weigh over 1.5 tone climbing a decent hill aswell but i agree with you chris on the chain size

[kelvin]

will start on the hull soon i have finished designing it

[chris davison]

If you can give me your hull measurements I can calc. the boyancy and then your safe payload.

[kelvin]

sorry Chris its all in mm
The width is 1100 if you could work it out that would be awsome

[chris davison]

I can calc it in MM What is your est. weight also? your width is 43.3 inches. Just remember there is 25.4 mm to an inch and you want to figure out how many cubic inches of water your hull will displace.