FIGURE 11.1 below shows a hydraulic lift. The lift needs to raise a maximum load of 34 000 N at the ram with a diameter of 250 mm. The force applied on the plunger is 215 N. Answer the questions that follow. Calculate the following: 11.1.1 The fluid pressure in the hydraulic system in MPa 11.1.2 The diameter of the plunger in mm 11.2 Name TWO types of hydraulic filters. 11.3 Identify the hydraulic symbols in FIGURES 11.3.1 and 11.3.2 below. 11.3.1 11.3.2

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FIGURE 11.1 below shows a hydraulic lift - NSC Mechanical Technology Fitting and Machining - Question 11 - 2022 - Paper 1

Question 11

FIGURE 11.1 below shows a hydraulic lift. The lift needs to raise a maximum load of 34 000 N at the ram with a diameter of 250 mm. The force applied on the plunger i... show full transcript

Worked Solution & Example Answer:FIGURE 11.1 below shows a hydraulic lift - NSC Mechanical Technology Fitting and Machining - Question 11 - 2022 - 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 ( P ) in the hydraulic system, use the formula:

P = \frac{F}{A}

where:

F is the force applied (215 N)
A is the cross-sectional area of the plunger.

The area (A) can be calculated using the diameter of the ram (D = 250 mm). First, convert D into meters:

D = \frac{250}{1000} = 0.25 \, m

Area is calculated as:

A = \frac{\pi D^2}{4} = \frac{\pi (0.25)^2}{4} \approx 0.0491 \, m^2

Now substitute A back into the pressure formula:

P = \frac{215}{0.0491} \approx 4387.18 \, Pa = 4.39 \, MPa

Step 2

11.1.2 The diameter of the plunger in mm

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Answer

To find the diameter of the plunger ( d d), use the principle of hydraulic systems, which states that:

\frac{F_1}{A_1} = \frac{F_2}{A_2}

For our case:

F1 = 215 N (force on the plunger)
F2 = 34,000 N (force on the ram)

Calculate Area:

$A_1 = \frac{\pi d^2}{4}$
$A_2 = \frac{\pi D^2}{4}$
Substitute A1 and A2 into the proportionality equation:

\frac{215}{\frac{\pi d^2}{4}} = \frac{34,000}{\frac{\pi (0.25)^2}{4}}

Cancel the common terms and solve for d:

\frac{215}{d^2} = \frac{34,000}{0.0154}

Rearranging gives:

$d^2 = \frac{215 \times 0.0154}{34,000}$ $d^2 \approx 0.0001 \, \Rightarrow \ d \approx 0.01 \, m = 10 \, mm$

Step 3

11.2 Name TWO types of hydraulic filters.

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Answer

Screen Filters: These retain large particles in the hydraulic fluid, preventing them from damaging the system.
Cartridge Filters: These are replaceable filter media that trap fine particles and contaminants, ensuring clean fluid circulation.

Step 4

11.3 Identify the hydraulic symbols in FIGURES 11.3.1 and 11.3.2 below.

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Answer

11.3.1: Filter Symbol - This symbol represents a hydraulic filter used to clean the fluid.

11.3.2: Pump Symbol - This symbol indicates a hydraulic pump that transfers hydraulic fluid within the system.

FIGURE 11.1 below shows a hydraulic lift - NSC Mechanical Technology Fitting and Machining - Question 11 - 2022 - Paper 1

Worked Solution & Example Answer:FIGURE 11.1 below shows a hydraulic lift - NSC Mechanical Technology Fitting and Machining - Question 11 - 2022 - Paper 1

11.1.1 The fluid pressure in the hydraulic system in MPa

11.1.2 The diameter of the plunger in mm

11.2 Name TWO types of hydraulic filters.

11.3 Identify the hydraulic symbols in FIGURES 11.3.1 and 11.3.2 below.

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