Who does a gearbox have 3 gears?

[Boo-Sabum Ben]

Just a thought, but why are standard gearboxes designed the way they are? As far as I understand, ever gear that's added to the system increases the effort needed to pull the piston back.

Would it not be far more efficient, and far simpler, to have a design where the fear that touches the pinion gear on the motor be the same gear that pulls back the piston, and having one large all in one gear rather than 3?

[jonny lovegrove]

Re: Who does a gearbox have 3 gears?

suspect its all to do with size restrictions and ratios and the like. easier for a geared motor to pull the spring back.

[Lee 303]

Re: Who does a gearbox have 3 gears?

Some have 4 gears like the MP7 and the Real Sword SVD

[tackle]

Re: Who does a gearbox have 3 gears?

In layman's terms:
Ever seen an "old skool" rope pulley, sometimes still seen on yachts/sailing boats, rope runs backwards & forward through a number of opposed wheels, allowing you to move a large weight or pull a large sail, often against a high wind, with very little effort, yet to do the same thing using your bare hands would prove difficult, maybe even impossible.
Gearboxes are much the same, trying to compress a high tensile steel spring requires considerable force, try it yourself, its heavy going, then imagine trying to do it 20 times a second, maybe for 6-8 seconds, even in bursts that's a lot of power needed, imagine playing with a BIG car battery in your backpack & your pistol grip needs to be big enough to take a washing machine motor, those are the dimension's we're talking about for a direct drive gearbox, which would prob still tear itself apart every couple of hours.
Hence the number of gears, a glorified but supremely effective winch to pull back the cylinder/spring.
Which is why I tell people to leave a working box alone, don't risk its reliability for the sake of a few more fps, its a design masterpiece & if it ain't broke don't fix it.
Hope that helps.

[Boo-Sabum Ben]

Re: Who does a gearbox have 3 gears?

Ah that's a good point. I had not thought about the resistance of the spring. Just the movement of the piston. Doh.

[Cayuse]

Re: Who does a gearbox have 3 gears?

Pinion gear is far to small and weak to pull back the spring alone. By all means take parts out and you will soon see every part is needed.

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[dadio]

Re: Who does a gearbox have 3 gears?

Fairly soon we might see the motor being replaced with a brushless motor that could be 1/3 or more smaller but the weak point has always been the gears , they have to be that size to be strong enough to pull the spring unless you go to exotic materials that cost the earth ! it's mechanical advantage or the old saying "Give me a big enough hammer and a place to stand and i could fix the whole world"

[dumpstafunk]

Re: Who does a gearbox have 3 gears?

I agree, in the RC hobby the brushless motor is a much more efficient and effective motor but the only problem is that you would then need a ESC (electronic speed control) or a computerized mosfet of some sort also.


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