**MET230: Hydraulics and Pneumatics**

MET230: Hydraulics and Pneumatics Week 1 Review Assignment

**Problem 1**

A hydraulic fluid has a specific weight of 60 lb/ft^{3}. What is its specific gravity SG? What is its density ρ?

**Problem 2**

Eleven liters of SAE 30 oil weighs 92 N. Calculate the oil’s

a. Specific weight

b. Density

c. Specific gravity

**Problem 3**

Convert a -6 kPa (negative 6 kiloPascal) pressure to an absolute pressure in kPa.

**Problem 4**

A hydraulic cylinder has a 275 mm diameter. How much oil pressure P (kPa) is required to produce 12500 N force at its piston?

**Problem 5**

An oil (SG = 0.87) has a viscosity of 187 SUS at 120 ^{o}F. Find the corresponding viscosity in units of cS (centiStokes) and cP (centiPoise).

**Problem 6**

In the hydraulic jack shown, a force of 100 N is exerted on the small piston. Determine the upward force on the large piston. The area of the small piston is 65 cm^{2}, and the area of the large piston is 950 cm^{2}. If the small piston moves 12 cm, how far will the large move? Assume the oil to be incompressible.**Problem 7**

The pneumatic/hydraulic system shown is use to lift a load. If the inlet air pressure is 450 kPa, determine the maximum load that can be lifted.

**Problem 8**

What is the theoretical flow rate from a fixed displacement axial piston pump with an eight-bore cylinder operating at 1750 rpm? Each bore has a 1.25-in diameter and the stroke of 0.75 in.

**Problem 9**

A vane pump is to have a volumetric displacement of 10 in^{3}. It has a rotor diameter of 2in, a cam ring diameter of 4in, and a vane width of 2.5 in. what must be the eccentricity?

**Problem 10**

Find the offset angle for an axial pump that delivers 50 gpm at 1750 rpm. The volumetric efficiency is 95%. The pump has a nine 0.75 inch diameter pistons arranged on a 6-in piston circle diameter.

**Problem 11**

A gear pump has a 75-mm outside diameter, a 55-mm inside diameter, and a 30-mm width. If the actual pump flow rate at 2700 rpm and rated pressure is 0.0025 m^{3}/s. What is the volumetric efficiency?

**Problem 12**

A pump has a displacement volume of 122 cm^{3}. It delivers 0.0027 m^{3}/s of oil at 1720 rpm and 85 bars. If the prime mover input torque is 175 N∙m

a. What is the overall efficiency of the pump?

b. What is the theoretical torque required to operate the pump?

**Problem 13**

A pump supplies oil at 25 gpm to a in diameter double acting hydraulic cylinder. If the load is 1800 lb (extending and retracting) and the rod diameter in, find the

a. Hydraulic pressure during the extending stroke

b. Piston velocity during the extending stroke

c. Cylinder horsepower during the extending stroke

d. Hydraulic pressure during the retracting stroke

e. Piston velocity during the retracting stroke

f. Cylinder horsepower during the retracting stroke