Gentlemen,
I have been lucky enough to find a UN1-04 for very very few bucks.....30 euros :2thumbsup:....
By the way, I found a place with 4 or 5 UN1-04 sold for 225 euros per unit. If someone could be interested, I may help.
To turn back to our torque discussion :
I measured the original 5th gear wheels (0.82 ratio) and the new set (0.76 ratio).
(0.82) :
Pinion (Input) : 7.6 cm, Wheel (Output) : 6.1 cm.
(0.76) :
Pinion (Input) : 7.9 cm, Wheel (Output) : 5.8 cm.
Let's remind some basic laws for calculating torque and force through wheels and pinion :
The pinion apply a force to the wheel, this makes the wheel to turn.
The force transmitted by a wheel is inversely proportional to the radius of the wheel. Plus the wheel is large, the less the force it sends is important, for a given torque.
The force applied to the wheel produces a torque. The torque is proportional to the radius of the wheel. Apply a force to a large wheel generates more torque than if one applies the same force to a small.
Now the formulas (quite simple) :
Force applied by pinion to wheel (f)= Torque (T1) at the center of the pinion / radius of the pinion (R1).
Torque trasmitted at the center of the wheel (T2) = (f) x radius of the wheel (R2).
Let's apply these formulas to our 0.76/0.82 ratio.
For the comparison, we will use a same theorical input torque (T1) of 100.
(0.82) :
Pinion (Input) : 7.6 cm, Wheel (Output) : 6.1 cm.
R1 = 3.8 cm (7.6 cm/2), R2 = 3.05 cm (6.1 cm/2).
f (force) = T1/R1 = 100/3.8 = 26.3.
T2 (output torque) = f * R2 = 26.3 * 3.05 = 80.3.
In this configuration, a given torque of 100 on pinion will generate a force of 26.3 and an output torque of 80.3 at the center of the wheel.
(0.76) :
Pinion (Input) : 7.9 cm, Wheel (Output) : 5.8 cm.
R1 = 3.95 cm (7.9 cm/2), R2 = 2.9 cm (5.8 cm/2).
f (force) = T1/R1 = 100/3.95 = 25.3.
T2 (output torque) = f * R2 = 25.3 * 2.9 = 73.4.
In this configuration, a given torque of 100 on pinion will generate a force of 25.3 and an output torque of 73.4 at the center of the wheel.
0.76 set will generate less torque and force than the 0.82 set.
For Bruce, I also measured the 1st gear pinion and wheel to illustrate these formulas to bring you the more accurate answer.
(1st gear) :
Pinion (Input) : 3 cm, Wheel (Output) : 10.7 cm.
R1 = 1.5 cm (3cm/2), R2 = 5.35 cm (10.7 cm/2).
f (force) = T1/R1 = 100/1.5= 66.7.
T2 (output torque) = f * R2 = 66.7 * 5.35 = 356.7
This is why, for a given torque you may apply by hand (our example of 100) to the input shaft, it is easier to make the 1st gear to turn, you hold a force of 66.7 while you only hold a force of 26.3 on the 5th gear pinion.
I hope my explanations to be of sense in english....:huh:
Cheers
Stephane
PS : I forgot tomention the legend as N or Nm. Force has to be expressed in Newtons while torque is expressed in Newton per distance : Newton per meter, Newton per centimeter.......:thumbsdown: