Week 2 Review Assignment

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School

ECPI University *

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230

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Mechanical Engineering

Date

Dec 6, 2023

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MET230: Hydraulics and Pneumatics Week 2 Review Assignment Problem 1 A rotary actuator has the following physical data: Outer radius of rotor = 0.75 in Outer radius of vane = 1.5 in Width of vane = 0.75 in If the torque load is 1000 in ∙ lb, what pressure must be developed to overcome the load? Answer = 1580psi Problem 2 A hydraulic motor has 7.5-in 3 volumetric displacement. If it has a pressure rating of 1200 psi and receives oil from a 25-gpm theoretical flow-rate pump, find the motor a. Speed = 770rpm b. Theoretical torque = 1194inlb c. Theoretical horsepower = 14.59HP Problem 3 A hydraulic motor has a displacement of 165 cm 3 and operates with a pressure of 98 bars and a speed of 1725 rpm. If the actual flow rate consumed by the motor is 0.0055 m 3 /s and the actual torque delivered by the motor is 210 N ∙ m, find a. η v = 86.2% b. η m = 81.6% c. η o = 70.3% d. kW power delivered by the motor = 37.93 kw Problem 4 A hydraulic transmission operating at 110-bars pressure has the following characteristics __________________________________________ Pump motor____ V D = 65 cm 3 V D = ? η v = 86% η v = 93% η m = 92% η m = 89% N = 1740 rpm N = 550 rpm__ Page 1

Find the a. Displacement of the motor = 164cm3 b. Motor output torque = 255.14Nm Problem 5 A pressure relief valve has a pressure setting of 850 psi. Compute the horsepower loss across this valve if it returns all the flow back to the tank from a 180-gpm pump. An unloading valve is used instead to unload the pump. If the pump discharge pressure during unloading equals 50 psi, how much hydraulic horsepower is being wasted? Answer = 89.26 HP Answer = 5.25 HP Problem 6 The system shown below has a hydraulic cylinder with a suspended load W. The cylinder piston and the rod diameters are 2.5 in and 0.25 in respectively. The pressure relief valve setting is 1600 psi. Determine pressure p 2 for a constant cylinder speed if a. W = 575 lb = 1734psi b. W = 0 (load is removed) = 1616psi Figure for Problem 6 Problem 7 A double-acting cylinder is hooked up in the regenerative circuit shown. The relief valve setting is 110 bars. The piston area is 300 cm 2 and the rod area is 65 cm 2 . If the pump flow is 0.0085 m 3 /s, find the cylinder speed and load-carrying capacity for the a. Extending stroke = 1.308 m/s, 77,000N Page 2

b. Retracting stroke = 0.362m/s, 258,500N Problem 8 For the system shown (for the extension strokes of the cylinders), what pump pressure is required if the cylinder loads are 12000 lb each and cylinder 1 has a piston diameter of 6in? Answer = 849psi Problem 9 a. Calculate the required size of a receiver that must supply air to a pneumatic system consuming 25 scfm for 12 min between 180 psi and 155 psi before the compressor resumes operation. Answer = 176.4ft3 b. What size is required if the compressor is running and delivering air at 12 scfm? Answer = 91.728ft3 Problem 10 Air at 110 o F passes through a 1 2 -in-diameter orifice having a flow capacity constant of 3.5. If the upstream pressure is 1500 psi, what is the maximum flow rate in units of scfm of air? Answer = 2515.764scfm Page 3

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