Question Without Notice

Wombat 280 · Guru

Question Without Notice

GaryKelly · Guru

What kinda dumb question is that? Where else would you put the gear stick?

Mark · Senior Member

To transefer power from an engine through a series of ratios to deliver momentum to a final drive at various speeds.

How's that!! biggrin

Weedy Pigeon · Senior Member

The design function of a gear box is to avoid having a flywheel weighing half a ton to move a stationery vehicle. Instead of storing momentum in a huge piece of spinning iron the gear box allows torque to be delivered at different rates to the driving wheels.
At least that was what I was taught when I did my apprenticeship in 66.
Lots of objects that can be driven didn't have a gear box but you wouldn't want to drive one to the local store for your bread and milk.

rockylizard · Guru

Gday...

Have a gander at this - http://www.mech.uq.edu.au/courses/mech3100-old/gearbox/s1.htm

Cheers - John

GaryKelly · Guru

That's interesting about the flywheel. I'm pretty sure steam locos don't have a gear box. That first "choof" sounds pretty painful but they eventually get going and some can hit 80 or 90mph! Marvelous things but as you say, not quite suitable for nicking up to the corner shop.

Magnarc · Guru

Gary, as an old fireman on BR steam locos I can assure you that they could reach well over a hundred mph. I lost a lot of sweat trying to keep the coal fed into the firebox of a A4 on the East coast main line.

PS. The world record speed for steam is held by the Gresley A4 Mallard. 126 mph down the Stoke Bank at Essendine, Nr Grantham. I'll bet the poor bugger who fired that was a few stone lighter when he finished!!!!

spida · Guru

So what did my CVT nissan have - i was told it was like a rubber band moving on a cone???? Sound about right - so no gear box as such?

Weedy Pigeon · Senior Member

spida wrote:
So what did my CVT nissan have - i was told it was like a rubber band moving on a cone???? Sound about right - so no gear box as such?

You have a Constantly Variable Transmission. It's a very old type of transmission that uses 2 tapers, one driven by the motor the other driving the wheels.

When maximum torque is required the belt is on the smaller end of the driving cone and the larger end of the driven cone. As the torque requirements become less the belt moves to the middle of the cones.

It's still gearing, except there's no box full of gears which require changing by hydraulic pressure, electric solenoid or manual shift by gearstick.

mr glassies · Guru

not so old weedy some motor scooters still use it i had a bobcat used the same system but it was hydraulic forced in and out its called variable speed

dibs

elliemike · Guru

DAF had a Variomatic Variable speed unit in a car it was still in use in the 70's. Just read up that Volvo used the DAF unit as well for a while.

Weedy Pigeon · Senior Member

mr glassies wrote:
not so old weedy some motor scooters still use it i had a bobcat used the same system but it was hydraulic forced in and out its called variable speed

dibs

I probably should have said that it is not a new invention rather than being "old ". If anyone is interested the best example that I can think of is in the top of a bench drill, not exactly the same but shows the principle of different sized driving and driven pulleys.

Wombat 280 · Guru

You obviously aren't reading the question correctly . Answer To hold oil Don't feel left out of the loop this was a question posed to a group of mech engineering students most of whom wrote no less than 1.5 pages on the gearbox but missed it's most basic design function, to hold oil

Mark · Senior Member

elliemike wrote:
DAF had a Variomatic Variable speed unit in a car it was still in use in the 70's. Just read up that Volvo used the DAF unit as well for a while.

LOL............ We used to call them Daf-odill's as they sold a lot of yellow ones.

rockylizard · Guru

Wombat 280 wrote:

You obviously aren't reading the question correctly . Answer To hold oil Don't feel left out of the loop this was a question posed to a group of mech engineering students most of whom wrote no less than 1.5 pages on the gearbox but missed it's most basic design function, to hold oil

Gday...

Interesting the question posed seeks to advise that the "design function" of a gearbox is to only hold oil. So I guess if, when the mechanic services/repairs my 'gear box' and he removes all the innards but leaves the oil in, he has achieved the correct 'design function' for my 'gear box'. Gawn ... ya joken surely ??

Perhaps this definition gives a deeper, and more correct scope of design function.

functional design-

A level of the design process in which subtasks are specified and the relationships among them defined, so that the total collection of subsystems performs the entire task of the system.

Cheers - John