Multistage cylinders are generally used to lift and tilt heavy loads under controlled speed. In defence applications multistage cylinders are used in missile tilt platform and antenna mast. Earth moving equipment’s such as tippers, dumpers, cranes and compactors uses multistage cylinders for operations. In the present work multistage hydraulic cylinder (telescopic cylinder) with three stage has been analysed using strain energy method and verified with finite element analysis. The research work investigates the effect of internal clearances which reduces the critical buckling load of hydraulic cylinders. The results are validated by buckling load test. The clearances between the tube to piston guides, gland guide to piston rod, clearances due to tube expansion under pressure, initial curvature in the tube, eccentricity of cylinder components and tube ovality are considered in the buckling load test. Describes the comparative study of buckling load tests of three stage hydraulic cylinders having fixed free and hinged mounting with five different internal clearances.<br /><br />
The Integrated Nozzle Actuating System (INAS) of a gas turbine engine is used to vary the exhaust nozzle area to achieve an optimum performance. The nozzle actuating system is operated by four actuators driven by an Integrated Hydraulic Power Pack (IHPP) connected to the Engine Gear Box (EGB). The quality of the oil operating the precision hydraulic actuators of the INAS should be maintained contamination free to achieve an optimum efficiency of the actuators. Hence a fine hydraulic filter is used in the IHPP circuit to maintain the cleanliness level of the hydraulic oil operating the actuators. The design and development of a hydraulic filter for an aircraft engine is a challenging task involving material selection, manufacturing process quality control and stringent performance qualification test schedule to follow the International standards. The present work describes the development of a 10 micron hydraulic filter operating at 30 bar pressure with a flow of 20 lpm designed according to the specifications of a typical aircraft gas turbine engine IHPP system. The filter has been qualified through all the tests prescribed by the International MIL-F-8815E standards. The tests like Multi-pass test, cold start test, Flow fatigue test, extreme temperature test, vibration test and bubble point test are described and the results are discussed.
The Fighter aircraft transmission system consists of a light weight, High Speed Flexible Coupling (HSFC) known as Power Take-Off shaft (PTO) for connecting Engine gearbox (EGB) with Accessory Gear Box (AGB). The HSFC transmits the power through series of specially contoured metallic annular thin flexible plates whose planes are normal to the torque axis. The HSFC operates at high speed ranging from 10,000 to 18,000 rpm. The HSFC is also catered for accommodating larger lateral and axial misalignment resulting from differential thermal expansion of the aircraft engine and mounting arrangement. The contoured titanium alloy flexible plates are designed with a thin cross sectional profile to accommodate axial and parallel misalignment by the elastic material flexure. This paper investigates the effect of misalignment on the transmission characteristics of the HSFC couplings. A mathematical model for the HSFC coupling with misalignment has been developed for analyzing the torque transmission and force interaction characteristics. An extensive testing has been conducted for validating characteristics of the designed coupling under various misalignment conditions. With this the suitability of the model adapted for the design iteration of HSFC development is validated. This method will reduce the design iteration cycles of HSFC and can be extended for the similar development of flexible couplings.
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