Old Suffolk Punch recoil starter versus rope kind

[MM]

All the farmers' tractors in rural Kent during my youth (late 1950s) had a large tank of paraffin and a very small tank of petrol. I didn't know of any tractor that ran purely on petrol.

MM

[The Natural Philosopher]

Mmm. I think there were a few.

?v=FF05PWVO_Dc&feature=relatedlooks like they were fairly common in the 40s and 50s

Probably phased out when taxation on petrol and road diesel made red diesel and TVO far more sensible

[Muddymike]

No. The first video clearly shows a petrol/TVO tractor. You can see the two tanks and the switch over valve in the video.

I love the second on. A tractor with a small block Chevy V8!!! What a conversion, love it.

Mike

[Muddymike]

When my son and I were unable to buy petrol whilst driving a Land Rover around Lesotho a few years ago we resorted to running on paraffin. Luckily the Land Rover had twin tanks so I filled one with paraffin and kept what little petrol we had left in the other tank for cold starting, just had to remember to run the paraffin dry before switching off!

Mike

[Huge]

Saw this (or at least, the latest incarnation) on Saturday;

[The Natural Philosopher]

Fro what I can glean that model was sold in two versions on TVO/petrol and one petrol only.

IS it a conversion?

[Muddymike]

There were actually three engine options. They were defined as Petrol, Petrol/VO and Lamp oil but the one in the you tube link you provided was definitely a petrol/VO engine.

He, he. You are kidding right? Tubular headers and an Edelbrock in a tractor :-)

Mike

[Tim Lamb]

In message , Muddymike writes

Death trap with the tow hitch above the axle and no roll bar.

I believe the TE20 was originally fitted with a version of the Standard Vanguard engine.

regards

[Andy Champ]

That sounded right for a moment. Then I thought...

The forward thrust is at ground level. The backwards pull at hitch, so you get a torque that lifts the front.

What difference does the axle make? (except as an indicator that the hitch is pretty high)

With you on the roll bar though...

Andy

[Dave Liquorice]

Move the hitch below the axle and do the same excercise...

Makes me very nervous when I see a tractor sans roll bar.

[Tim Lamb]

Wheel torque refers through the axle. If you attach something immovable above the torque available in low gear will tip the vehicle over backwards. Happened to a school acquaintance.

regards

[The Natural Philosopher]

but that is independent of the hitch points exact location. although the higher it is the worse it is.

The actual centre of rotation for a wheelie is where the ground meets the rear tyre.

I.e. the only safe hitch point that wont cause a wheelie is ground level. To make it slam the front tyres down, BELOW ground level is good :-)

[Andy Champ]

For your and Tim's education... (TNP has it right)

The forward thrust is where the tyre meets the ground.

The backward thrust is at the hitch.

The torque is obtained by multiplying the force by the distance between the two points (assuming the pull is parallel to the ground)

The effect is the same regardless of the size of the wheels, or the height of the axle.

Remember - every couple has its moment in a field.

Andy

[Tim Lamb]

It is 50 years since I knew anything about *moments*!

Surely the vehicle can only rotate about the axle?

You have a forward moment parallel with the ground and at the tyre contact point. You have a smaller, reverse one parallel to the ground and through the hitch.

If the reverse one is higher than the axle then they add; causing the front wheels to lift off the ground.

regards

[Tim Lamb]

:-)

Now take the case where the above axle hitch is attached to an immovable object...

regards

[Nick Odell]

Instinct and practical experience tell you that you are right but the principles of moments are no respecters of instinct and practical experience.

Imagine that instead of the tractor pulling the load, the load is pulling the tractor - for the purposes of the forces involved, it doesn't matter where they originate. Lock the tractor wheels and the load will pull the tractor back into a wheelie and the fulcrum will be the point of contact of the rear wheel tyre with the ground.

You could pull the tractor into a wheelie quite easily if the cable were attached to the top of the cab and it would get progressively harder to do, the lower the point of attachment. The forces required to produce a wheelie if the point of attachment were, say, two inches above the ground, would be massive and the tractor would probably break up before it rose up but in principle there would still be a turning force around the edge of the tyre.

Nick (who's recently been playing with force diagrams to try and work out why some guitar necks break in transit and whether relaxing the string tension would make any difference (answer: not a lot (but altering the packaging might)))

[The Natural Philosopher]

No.

There is no such thing as a forward moment. Moments come in clockwise or anti clockwise. From a given orientation.

The drive of the tractor gives a moment that tends to lift the fromt wheenl under acceleration. This is not 'about' the front wheel axle, or about the back wheel axle, it is about the point of the tractor that is 'fixed' to the ground. The rear tyre contact patch.

Any drag above that will make the tendency worse. So any hitch will tend to flip the tractor - but the lower it is the less it will do it

You have a smaller, reverse one parallel to the ground

Or a reverse moment.

then they add; causing the

Think if the case where you have three axles driving a caterpillar tread. Which "axle" do you think it will rotate round and why, if pulling at a heavy tow ? Since any one of the three could be driven and be 'applying torque' to the tracks, and the tracks are anything but round.

[The Natural Philosopher]

Are those acoustic guitars?

I know teh stresses and strains in leccy guitars very well.

And can guess at acoustics: definitely that's a packaging thing.

[Nick Odell]

It can be either: certain electric guitars have weaknesses in the woodwork beause of their slim build: acoustic guitars tend to be more solid in that respect but the strings are under greater tension.

When you do the force diagram thingey you discover that even though the string tension at the bridge might amount to about 150lbs (acoustic guitar) relatively little of that is acting in the directon of a potential break. Though string tension may be a contributing factor, I'm more inclined to blame heavy, cast-metal machine heads. Drop a box off the tailgate of a truck and the abrupt stop at the end leaves the best part of a kilo of concentrated mass still trying to force its way down to the centre of the Earth. Packing so that the headstock cannot move at all relative to the neck should absorb that energy less harmfully, IMO.

Nick

[Tim Lamb]

In message , The Natural Philosopher writes

OK all. Points taken.

I think my error stems from HSE leaflets on safe hitching.

I'm too old to go back and learn anything about moments now!

regards