computerized gear system

SUBJECT : ENGINEERING LABORATORY IV (BDA 2721)

CODE : BDA 2711

TOPIC : COMPUTERIZED GEAR SYSTEM

OBJECTIVES :

i. Describe the different type of gear system and some of their application

ii. Calculate gear ratios, angular velocity, input and output torque.

iii. Calculate the efficiency of the gears.

LEARNING OUTCOMES :

i. Understand the concept of gear system, types of gears and its related function and

application.

ii. Implement and analyze the required data collectively within member of group.

iii. Produce good technical report according to the required standard

THEORY :

Gears are used to transmit motion, and therefore power, between one shaft and

another shaft. The function of a gear box is to transmit rotational motion from a

driving prime mover to a driven machine. Gear also know as a toothed wheel

designed to transmit torque to another gear or toothed component. Different size gears

are often used in pairs, allowing the torque of the driving gear to produce a large

torque in the driven gear at lower speed, or a smaller torque at higher speed. The large

gear known as wheel and the smaller gears as a pinion. Consider a simple schematic

of a gear box with an input and output shaft as shown in Figure 1.

Figure 1

N1

N2

And another theory of gear is a component within a transmission device that transmits

rotational torque by applying a force to the teeth of another gear or device. A gear is different

from a pulley in that a gear is a round wheel that has linkages ("teeth" or "cogs") that mesh

with other gear teeth, allowing force to be fully transferred without slippage. Depending on

their construction and arrangement, geared devices can transmit forces at different speeds,

torques, or in a different direction, from the power source.

The gear's most important feature is that gears of unequal sizes (diameters) can be combined

to produce a mechanical advantage, so that the rotational speed and torque of the second gear

are different from those of the first. In the context of a particular machine, the term "gear"

also refers to one particular arrangement of gears among other arrangements (such as "first

gear"). Such arrangements are often given as a ratio, using the number of teeth or gear

diameter as units.

Gear Types

internal gears Worms Gear

Spur gears

Bevel gears

http://en.wikipedia.org/wiki/Mechanical_advantage

http://en.wikipedia.org/wiki/Torque

http://en.wikipedia.org/wiki/Speed

http://en.wikipedia.org/wiki/Pulley

http://en.wikipedia.org/wiki/Rotation

http://en.wikipedia.org/wiki/Transmission_(mechanics)

Gear ratio, G.R = Input Speed / Output Speed, = N1 / N2

Gear ratio, G.R = (product of driven teeth)/(product of driving teeth)

Gear ratio, G.R = Input Speed / Output Speed, = ω1 / ω2

The power transmitted by a torque,T (Nm) applied to the shaft rotating at N (rev/min) is given by :-

Power, P = TωP = [ 2πNT] / 60

In the ideal gearbox, the input and output power are the same so,[2πN2T2] / 60 = [2πN1T1] / 60

In a real gear box, power is lost through friction and the power output is smaller than the power input.

The efficiency is defined as;η = Power Output / Power Inputη = [2πN2T2 x 60] / [2πN1T1 x 60]η = T1ω1 / T1ω1

Note:- N – speed in rev/min ω – angular velocity (rad/s)

Table 1 : Technical Specification for EquipmentType

of Gear

Class of Gear

DescriptionGear

1 2 3 4

4 - Stage

Same Size

a. No of teeth

18 78 78 78

b. Pitch diameter

36 156 156 156

c. Outside diameter

40 160 160 160

4 - Stage

Different Size

a. No of teeth

18 38 78 118

b. Pitch diameter

36 76 156 232

c. Outside diameter

40 80 160 236

EQUIPMENT :

ITEM NO

Unit of Gear Set 2

Control Panel 1

Computer Set 1

Printer 1

Protective Transparent Cover 1

Equipment

Motor

Potentiometer

Gear Set Speed Set

Motor DisplayMotor Driver Computer

Figure 2 : Connection Diagram

Protective transparent cover Control Panel

Unit of Gear set

Main Table

Table

CPU Figure 3 : Overall System

Protective transparent

Control Panel

Gear Set Main Table

Computer

PROCEDURES :

A. EXPERIMENT FOR 4 STAGE GEAR WITH SAME SIZE GEAR - GEAR SET 1

1) Make sure gear set 1 is in place. If not, install the gear set 1 into the system according

to the following steps:-

i. Remove the transparent protective cover of the system.

ii. Disconnect the sensor cable. Remove the locking bolts of the gear set.

iii. Remove the gear set by lifting it using the handles.

iv. Put the removed gear set lifting on storage table.

v. Take the new gear set and put it on system. Make sure the gear set is

completely in place.

vi. Tighten the locking bolts. Connect the sensor cable.

vii. Put the transparent protective cover of the system. The new set is ready to

operate.

2) Turn on the computer. Turn on the Infix gear software.

3) Turn on the system by pressing ON button. The controller and motor displays will

ON.

4) Slowly increase the speed until it reaches 100rpm. Record the motor speed into the

lab sheet accordingly.

5) Press RECORD on the monitoring page software. Let the system run and stabilize for

an about 10 seconds.

6) Slowly increase the speed until it reaches 200rpm. Record the motor speed into the

lab sheet 1.

7) Let the system run and stabilize for about 10 seconds.

8) Follow the step 5.1.6 to 5.1.7 for the speed adjustment of 300rpm, 400rpm, 500rpm,

600rpm, and 700rpm.

9) Turn OFF the potentiometer slowly.

10) Record all values into your lab sheet.

B. EXPERIMENT FOR 4 STAGE GEAR WITH DIFFERENT SIZE GEAR –

GEAR SET 2

1) 5.2.1. Make sure gear set 2 is in place. If not, install the gear set 2 into the system

according to the steps 5.1.1. (i – vii).

2) 5.2.2. Turn on the computer. Turn on the Infix gear software.

3) 5.2.3. Turn on the system by pressing ON button. The controller and motor displays

will ON.

4) 5.2.4. Slowly increase the speed until it reaches 100rpm. Record the motor speed

into the lab sheet accordingly.

5) 5.2.5. Press RECORD on the monitoring page software. Let the system run and

stabilize for an about 10 seconds.

6) 5.2.6. Slowly increase the speed until it reaches 200rpm. Record the motor speed

into the lab sheet 1 accordingly.

7) 5.2.7. Let the system run stabilize for about 10 seconds.

8) 5.2.8. Follow the step 5.1.6 to 5.1.7 for the speed adjustment of 300rpm, 400rpm,

500rpm, 600rpm, and 700rpm.

9) 5.2.9. Turn OFF the potentiometer slowly.

10) 5.2.10. Record all values into your lab sheet.

OBSERVATIONS :

TABLE 2 : 4 Stage Gear with Same Size Gear – Gear Set

Gear 0

( Motor )Gear 1 Gear 2 Gear 3

No of teeth (t) 18 78 78 78

Pitch Diameter (D) mm 36 156 156 156

Gear Ratio (Calculation) - 0.23 0.23 0.23

Speed (rpm) 100 23 5 2

200 46 11 2

300 70 16 4

400 92 22 5

500 115 27 6

600 138 32 8

700 162 38 8

Gear Ratio (From Data) - 0.23 0.05 0.01

Gear Efficiency - 0.87 0.84 0.87

TABLE 3 : 4 Stage Gear with Same Size Gear – Gear Set 2

Gear 0

( Motor )Gear 1 Gear 2 Gear 3

No of teeth (t) 18 38 78 118

Pitch Diameter (D) mm 36 76 156 232

Gear Ratio (Calculation) - 0.47 0.23 0.15

Speed (rpm) 100 48 12 2

200 95 23 4

300 143 34 5

400 189 42 6

500 237 55 7

600 285 66 11

700 332 78 14

Gear Ratio (From Data) - 0.23 0.05 0.01

Gear Efficiency - 0.87 0.87 0.87

Gear with different size make motor speed (Rpm) increase.

The value is not accurate and very sensitive to define.

Speed motor with same size or different size with Gear 0 to 3, the value of speed

motor from result will decrease until the lowest value in the data from Gear 0 to Gear

3

DISCUSSIONS :

i. From table 1 and 2, calculate the gear ratio theoretically and experimentally and compare the result.

From the data, the value from table 1 and 2 shows that the gear ratio of calculation and the gear ratio of theory are different.

It show that data with experimentally, that motor speed is higher than data With theory.it because depending with the size and teeth that we use to

Experiment

Gear Ratio (Calculation) 0.23 0.23 0.23

Gear Ratio (From Data) 0.23 0.05 0.01

Gear Ratio (Calculation) 0.47 0.23 0.15

Gear Ratio (From Data) 0.23 0.05 0.01

ii. From the experiments, plot the graph Speed (rpm) versus Time (seconds) of the Gear set 1 and 2. Review the results.

SET 1

SET 2

iii. What are the input torque and the output torque of the gear system. Given that the input power Pin equal to 20kW and the efficiency, ƞ equal to 0.7.

The value taken from data Table 1

Calculation For () Gear 0

Formula : 2πN/60

2 x π x 100 =10.47 rad/s

60

Calculation Torque (T) ,Given data input power =20kW

T=P/

T= 20kW/10.47

= 1910.2 Nm (input Torque)

The value taken from data Table 1


Formula : 2πN/60

2 x π x 23 = 2.408 rad/s

60

Calculation Tork (T) ,Given data input power =20kW

T=P/

T= 20kW/2.408

= 8305.6Nm (Output Torque)

The value take from data Table 1


Formula : 2πN/60

2 x π x 5 = 0.524 rad/s

60


T=P/

T= 20kW/0.524

= 38167.9 Nm (Output Tork)



Formula : 2πN/60

2 x π x 2 = 0.209 rad/s

60


T=P/

T= 20kW/0.209

= 95693.7 Nm (Output Torque)

Gear 0 Gear 1 Gear 2 Gear 3

N

(rpm)

Rad/s

T

(Nm)

N

(rpm)

Rad/s

T

(Nm)

N

(rpm)

Rad/s

T

(Nm)

N

(rpm)

Rad/s

T

(Nm)

100 10.47 1910.2 48 5.026 3979.3 12 1.256 15915.5 2 0.209 95693.7

200 20.94 955.10 95 9.948 2010.5 23 2.408 8305.6 4 0.418 47746.5

300 31.42 6365.3 143 14.97 1336.0 34 3.560 5617.9 5 0.523 38197.1

400 41.89 476.42 189 19.79 1010.6 42 4.398 4547.5 6 0.628 31847.1

500 52.36 381.97 237 24.82 805.8 55 5.760 3472.2 7 0.733 27285.1

600 62.83 318.32 285 29.85 670.0 66 6.911 2893.9 11 1.152 17362.3

700 73.30 272.85 332 34.76 575.37 78 8.168 2448.5 14 1.466 13641.8

Table 2: 4 stage Gear with Different size Gear - Gear Set 2



Formula : 2πN/60

2 x π x 100 =10.47 rad/s

60


T=P/

T= 20kW/10.47

= 1910.2 Nm (input Torque)



Formula : 2πN/60

2 x π x 48 = 5.026 rad/s

60


T=P/

T= 20kW/2.408




Formula : 2πN/60

2 x π x 12 = 1.256 rad/s

60


T=P/

T= 20kW/0.524




Formula : 2πN/60

2 x π x 2 = 0.209 rad/s

60


T= P/

T= 20kW/0.209


iv. Calculate the efficiency of the gear system (gear set 1 and 2) of the following combination gear :-

a. Gear 1 to gear 0b. Gear 2 to gear 0c. Gear 3 to gear 0

Set 1

Gear 0 – Gear 1 Gear 0 – Gear 2 Gear 0 – Gear 3

N (rpm) Gear Ratio η =efficency Gear Ratioη=efficenc

yGear Ratio η=efficency

100 0.23 1.0 0.05 1.0 0.02 1.0

200 0.23 1.0 0.06 1.0 0.02 1.0

300 0.23 0.1 0.05 0.1 0.01 0.1

400 0.23 1.0 0.06 1.0 0.01 1.0

500 0.23 1.0 0.05 0.8 0.01 1.0

600 0.23 1.0 0.05 1.0 0.01 1.0

700 0.23 1.0 0.05 1.0 0.01 1.0

Average

Gear ratio0.23 - 0.05 - 0.01 -

Average

Effeciency- 0.87 - 0.84 - 0.87

Set 2

Gear 0 – Gear 1 Gear 0 – Gear 2 Gear 0 – Gear 3

N (rpm) Gear Ratio η =efficency Gear Ratioη=efficenc

yGear Ratio η=efficency

100 0.23 1.0 0.05 1.0 0.02 1.0

200 0.23 1.0 0.06 1.0 0.02 1.0

300 0.23 0.1 0.05 0.1 0.01 0.1

400 0.23 1.0 0.06 1.0 0.01 1.0

500 0.23 1.0 0.05 1.0 0.01 1.0

600 0.23 1.0 0.05 1.0 0.01 1.0

700 0.23 1.0 0.05 1.0 0.01 1.0

Average

Gear ratio0.23 - 0.05 - 0.01 -

Average

Effeciency- 0.87 - 0.87 - 0.87

CONCLUSION :

From the experiment, the objectives have been achieved which are describing the different

types of gear system, calculating the ratios, angular velocity, input and output speed and

efficiency. From what I have learn to this experiment, this experiment similarly like system

gearbox in car is to transmit rotational motional from a driving prime mover to a driven

machine.

troubleshooting the software and the speed sensor so the value given are accurate and precise.

REFERENCES :

http://en.wikipedia.org/wiki/Gear

McGraw Hill Encyclopedia of Science and Technology, "Gear"

Gear Dive Systems: Design and Application, by Peter Lynwander

http://www.codecogs.com/reference/engineering/materials/

shear_force_and_bending_moment.php

http://en.wikipedia.org/wiki/Gear

computerized gear system

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