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Handbook of Mechanical Engineering Calculations P21

TRANSMISSIONS, CLUTCHES, ROLLER-SCREW ACTUATORS, COUPLINGS, AND SPEED CONTROL Constructing Mathematical Models for Analyzing Hydrostatic Transmissions | Source HANDBOOK OF MECHANICAL ENGINEERING CALCULATIONS __SECTION 21 TRANSMISSIONS CLUTCHES ROLLER-SCREW ACTUATORS COUPLINGS AND SPEED CONTROL Constructing Mathematical Models for Analyzing Hydrostatic Transmissions 21.1 Selecting a Clutch for a Given Load 21.12 Clutch Selection for Shaft Drive 21.13 Sizing Planetary Linear-Actuator Roller Screws 21.16 Designing a Rolling-Contact Translation Screw 21.21 Selection of a Rigid Flange-Type Shaft Coupling 21.30 Selection of Flexible-Coupling for a Shaft 21.32 Selection of a Shaft Coupling for Torque and Thrust Loads 21.34 High-Speed Power-Coupling Characteristics 21.35 Selection of Roller and Inverted-Tooth Silent Chain Drives 21.38 Cam Clutch Selection and Analysis 21.42 Timing-Belt Drive Selection and Analysis 21.43 Geared Speed Reducer Selection and Application 21.47 Power Transmission for a Variable- Speed Drive 21.48 CONSTRUCTING MATHEMATICAL MODELS FOR ANALYZING HYDROSTATIC TRANSMISSIONS Construct a mathematical model of vehicle performance for a construction vehicle powered by a hydrostatic transmission when the vehicle is driven by a 45-hp 33.6-kW engine at 2400 rpm with a high idle-speed of 2600 rpm. The vehicle has a supercharge pump rated at 2 hp 1.5 kW . Other vehicle data are loaded radius rL 14.5 in 36.8 cm gross vehicle weight W4 8500 lb 3825 kg weight on drive wheels Ww 5150 lb 2338 kg final drive ratio Rfd 40 1 coefficient of slip Cs 0.8 and coefficient of rolling resistance Cr 60 lb 1000 lb 27.2 kg 454 kg of gross vehicle weight. The vehicle is powered by a hydrostatic transmission with a 2.5-in3 rev 41-mL rev displacement pump rated at 5000 lb in2 34.5-MPa . Compare the performance produced by using a 2.5-in3 rev 41-mL rev displacement fixed-displacement motor and a 2.5-in3 rev 41-mL rev displacement variable-displacement motor with an 11-degree displacement stop. Other pump and motor data are given on performance curves available from the pump manufacturer. 21.1 Downloaded from Digital .