Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram 11.2 State ONE function of a hydraulic reservoir. 11.3 Give TWO reasons why pneumatic systems are very efficient. 11.4 State TWO uses of pneumatic systems. 11.5 A pulley with a diameter of 800 mm is mounted on a shaft of a washing machine. The washing machine is driven from a pulley with a diameter of 600 mm which rotates at a speed of 7.2 r/s. The tension force in the tight side of the belt is 300 N. The ratio between the tensile force in the tight side and slack side is 2.5 : 1. (Ignore belt thickness.) Determine the following by means of calculations: 11.5.1 The rotational frequency of the pulley on the washing machine in r/s 11.5.2 The power that can be transmitted in kW 11.6 FIGURE 11.6 below shows a gear drive system. Driver gear A on the shaft of the motor has 30 teeth and meshes with gear B with 40 teeth on the counter shaft. On the counter shaft is another driver gear, C, with 20 teeth that mesh with gear D with 60 teeth on the output. Calculate the following: 11.6.1 The rotation frequency of the output shaft if the motor rotates at 2300 r/min 11.6.2 The ratio between the input shaft and the output shaft of the system.

NSC Mechanical Technology Fitting and Machining Purpose and operation of various pumps: Calculate the following: 11.1.1

Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram 11.2 State ONE function of a hydraulic reservoir - NSC Mechanical Technology Fitting and Machining - Question 11 - 2021 - Paper 1

Question 11

Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The magnitude of the force that will be exerted onto the bearing by the ra... show full transcript

Worked Solution & Example Answer:Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram 11.2 State ONE function of a hydraulic reservoir - NSC Mechanical Technology Fitting and Machining - Question 11 - 2021 - Paper 1

Step 1

11.1.1 The fluid pressure in the hydraulic system in MPa

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Answer

To calculate the fluid pressure in the hydraulic system, we use the formula:

$P = \frac{F}{A}$

Where:

$F$ is the force in Newtons (25 kN or 25000 N), and
$A$ is the area of the plunger given by the formula $A = \frac{\pi d^2}{4}$ .

First, we calculate the area of the plunger:

Diameter $d = 35 mm = 0.035 m$
Area: $A = \frac{\pi (0.035)^2}{4} = 9.62 \times 10^{-4} m^2$

Now substituting into the pressure formula:

$P = \frac{25000}{9.62 \times 10^{-4}} = 25958.1 Pa = 25.96 MPa$

Step 2

11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram

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To find the force exerted by the ram, we can rearrange the initial formula where the area will be calculated with the diameter of the ram:

Diameter $D = 120 mm = 0.120 m$
Area of the ram: $A = \frac{\pi D^2}{4} = \frac{\pi (0.120)^2}{4} = 1.131 \times 10^{-2} m^2$

Using the pressure calculated in step 11.1.1: $F = P \times A = 25958.1 \times 1.131 \times 10^{-2} = 293,88 N$

Step 3

11.2 State ONE function of a hydraulic reservoir.

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Answer

One function of a hydraulic reservoir is to act as a fluid storage tank, which helps in maintaining a sufficient supply of hydraulic fluid for the system.

Step 4

11.3 Give TWO reasons why pneumatic systems are very efficient.

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Answer

Pneumatic tools are environmentally friendly, making them suitable for various applications.
They are easy to use and require less physical effort from the operator, thereby enhancing productivity.

Step 5

11.4 State TWO uses of pneumatic systems.

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Drills
Nail guns

Step 6

11.5.1 The rotational frequency of the pulley on the washing machine in r/s

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Answer

To find the rotational frequency of the pulley: Using the relationship between the diameters and speeds:

$N_1 D_1 = N_2 D_2$

Let $N_1$ be the speed of the driver pulley and $D_1 = 600 mm = 0.6 m$ , $D_2 = 800 mm = 0.8 m$ . The speed of the driver pulley is given as $N_1 = 7.2 r/s$ .

Now substituting: $N_2 = \frac{N_1 D_1}{D_2} = \frac{7.2 \times 0.6}{0.8} = 5.4 r/s$

Step 7

11.5.2 The power that can be transmitted in kW

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Answer

The power transmitted can be calculated using:

$P = T \times \frac{(T_1 - T_2) D N}{60}$

Where:

$T_1 = 300 N$ (tight side),
$T_2 = 120 N$ ,
$D = 0.8 m$ , and
$N = 5.4 r/s$ .

Now substituting:

$P = (300 - 120) \times 0.8 \times 5.4 = 2.44 kW$

Step 8

11.6.1 The rotation frequency of the output shaft if the motor rotates at 2300 r/min

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To find the output frequency:

Using: $N_{output} = \frac{T_A \times T_C \times N_A}{T_B \times T_D}$

Where gears have:

$T_A = 30$ , $T_B = 40$ , $N_A = 2300$ , $T_C = 20$ , and $T_D = 60$ .

Therefore:

$N_{output} = \frac{30 \times 20 \times 2300}{40 \times 60} = 575 r/min$

Step 9

11.6.2 The ratio between the input shaft and the output shaft of the system.

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Answer

The gear ratio can be calculated as:

$Gear\ Ratio = \frac{Product\ of\ teeth\ on\ driven\ gears}{Product\ of\ teeth\ on\ driver\ gears} = \frac{40 \times 60}{30 \times 20} = 4:1$

Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram 11.2 State ONE function of a hydraulic reservoir - NSC Mechanical Technology Fitting and Machining - Question 11 - 2021 - Paper 1

11.1.1 The fluid pressure in the hydraulic system in MPa

11.1.2 The magnitude of the force that will be exerted onto the bearing by the ram

11.2 State ONE function of a hydraulic reservoir.

11.3 Give TWO reasons why pneumatic systems are very efficient.

11.4 State TWO uses of pneumatic systems.

11.5.1 The rotational frequency of the pulley on the washing machine in r/s

11.5.2 The power that can be transmitted in kW

11.6.1 The rotation frequency of the output shaft if the motor rotates at 2300 r/min

11.6.2 The ratio between the input shaft and the output shaft of the system.

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