5. A) A mechanical energy storage device is designed to lift a large weight, thus

storing potential energy, using a screw jack mechanism.

The screw Jack has a pitch of 8 mm and a diameter of 60 mm. The force ratio,

including friction losses, is 0.15. The effort is applied through a lever of radius 350

mm.

i)

ii)

Calculate force required to raise a load of 400N

Examine the key differences between this mechanical energy

storage device and an energy storage flywheel

B) An alternative mechanism for raising the load uses a reduction gearbox as

shown below.

D₁

bet

(B)

D3

A

D4

++||

INPUT

OUTPUT/ni)

Engineer

1

2

3

4

5

6

Calculate the velocity ratio for the set of pitch circle sizes (in mm)

allocated to you by your manager from the table below:

D₁

D₂

D3

180

60

160

50

40

60

50

40

ii)

60

80

80

60

60

80

220

220

200

180

D4

140

150

130

110

120

130

If the input power is 20kW and the input shaft speed is 120

rev/minute, calculate the holding torque at an efficiency of 80%