1. MECH1200
Multiple gears
The Speed of any driven gear is determined by calculating the gear ratio using the driven gear as the output gear along with the input gear and ignoring all other gears in between
Note: Idlers in pulleys and sprockets are use to increase the TENSION on the belt or chain drives.

2. MECH1200
Whether an extra gear in a gear train is an idler or drives an extra shaft,
The method to determine speed and torque remains the same.
Idler gears do not affect torque or speed of the driven shaft
If you calculate the gear ratio by multiplying the ratios of each pair of neighboring gears together, the effect of the idle gears is canceled out

3. MECH1200
The number of teeth of both the idler gears is used twice in the formula. They cancel each other out.

4. MECH1200
The gear shown has three output gears, each of which drives a separate shaft with a separate load. It has one true idler gear.

5. MECH1200
The speed of each output shaft can now be calculated separately using its own gear ratio.
The idler gear has no effect on the speed of any output shaft.
The speed of one output shaft has no effect on the speed of the other output shafts because they act like idlers with respect to the other shafts.

6. MECH1200
Torque Review
Torque
Total Torque

7. MECH1200
Gear Ratio Review

8. MECH1200

9. MECH1200

10. MECH1200

11. MECH1200

12. MECH1200
Torque

13. MECH1200
Compound Gears
A compound gear drive is a type of gear train that has two or more gears mounted on one shaft
The gears can be mounted anywhere on the shaft, either next to each other or on opposite sides of the shaft.

14. Two applications of compound gears are:
MECH1200
Two applications of compound gears are:
Driving two output shafts at different speeds and driving an output shaft that is offset from the driver shaft.

15. This is call a reverted gear drive.
MECH1200
A third application of compound gear drives is to create a gear reduction between two shafts which are located on the same axis.
This is call a reverted gear drive.

16. Compound Gear Drive Speed
MECH1200
Compound Gear Drive Speed
Similar to calculations from before except the gear ratio of any gears that are mounted on the same shaft must be included in the calculation.

17. Idlers still have no effect.
MECH1200
These also are the same as simple gear drives except that they are multiplied by the gear ratio of the compound gears.
Idlers still have no effect.

18. MECH1200
Overall Gear Ratio is found using same driven/driver formula Rtot= NDVN1 NDVR1 x NDVN2 NDVR2 x NDVN3 NDVR3 x ………. or Rtot = R1 x R2 x R3 x R4 x …..x RN This is similar to overall efficiency: ηtot = η1 x η2 x η3 x η4 x …….. x ηN

19. MECH1200
Gear Ratio: Driven to Driver
R = 30:10 = 3:1
Gear Ratio: Compound Gears
R = 10:20 = 1:2
Compound Gear Ratio = 3:2
𝑅= 𝑆 𝑖𝑛𝑝𝑢𝑡 𝑆 𝑜𝑢𝑡𝑝𝑢𝑡
3:2= 𝑆 𝑜𝑢𝑡𝑝𝑢𝑡
𝑆 𝑜𝑢𝑡𝑝𝑢𝑡 = :2 =1200

20. Compound Gear Drive Torque
MECH1200
Compound Gear Drive Torque

21. What is the driven shaft’s speed?
MECH1200
What is the driven shaft’s speed?

22. MECH1200
What is the torque of the driven shaft?

23. What is the driver’s shaft speed?
MECH1200
What is the driver’s shaft speed?

24. What is the torque of the driver shaft?
MECH1200
What is the torque of the driver shaft?

25. What is the driver’s shaft speed?
MECH1200
What is the driver’s shaft speed?

26. What is the torque of the driver shaft?
MECH1200
What is the torque of the driver shaft?