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This report describes the results of an analytical study of the point efficiencies of various types of fuze gear trains. Involute and clock-tooth profiles for two and three pass step-up gear meshes which operate in spin and nonspin environments are compared, and the differences explored. The conclusions of an investigation concerning the geometrical factors which influence the point efficiencies of multipass step-up gear trains are discussed. The analyses on which these results are based are given in detail.

This report documents the development of tools needed to compare the efficiency of fuze-related gear trains designed to operate in a spin environment. Computer models have been developed for two and three pass step-up designs with clock (ogival) and involute tooth shapes. Using appropriate moment input-output relationships, the computer programs develop point and cycle efficiency for each type of gear train. Pivot friction partially caused by centrifugal force on the gear and pinion combinations during spin, and tooth-to-tooth contact friction are considered. All models allow a variety of parameter variations.

A computer simulation was developed for a complete artillery safing and arming (S&A) mechanism which must operate in a projectile that experiences spin, precession, and nutation. This mechanism contains a straight-sided verge runaway escapement, a two pass involute step-out gear train, and a spin driven rotor. The mathematical model treats three motion regimes of the associated escapement (i.e., coupled motion, free motion, and impact). The computer program is well adapted to parametric studies, and it allows the use of pallets with arbitrarily selected centers of mass. Also, when actual aeroballistics data are used, it determines the behavior of the S&A mechanism in a projectile with pathological motion. A sample simulation, with the dimensions of the M739 S&A mechanism, was run at 30,000 rpm with small precession and nutation velocities. It showed essentially the same number of turns-to-arm when only spin is present., See also ARLCD-TR-82013, AD-A123 341 and ARLCD-TR-81039, AD- A118 395.

This investigation developed a computer simulation which is adaptable to the two configurations of a complete artillery safing and arming mechanism that is driven by a rotor and contains a straight-sided verge runaway escapement and a two-pass involute gear train. The mathematical model treats three motion regimes of the associated escapement; i.e., coupled motion, free motion, and impact. The computer program is well adapted to parametric studies, and it allows the use of pallets with arbitrarily located centers of mass. Further, it makes it possible to determine the maximum value of the contact forces in the gear train as well as in the escapement. A simulation run with the dimensions of the M739 safing and arming mechanism showed excellent agreement with experimental results when a system coefficient of friction of 0.1 was used., See also AD-A118 395.

This investigation developed a workable computer simulation of the pin pallet runaway escapement which can provide the basis for the analysis and synthesis of various safing and arming devices. The dynamics of the various regimes of escapement motion are modelled. Coupled motion, impact, and free motion are considered. Sensing equations for the determination of the instantaneous positions of the pallet pin and the escape-wheel form the basis for the controls in the computer program. The simulation is applied to the timing of the mechanism of the M525 fuze with an assumption of constant input torque to the escape-wheel. The influence of changes on such parameters as escape-wheel torque, pallet moment of inertia, center distance, pallent radius, etc., are explored in detail by appropriate computer runs. Agreement has been found with existing experimental data. Finally, recommendations for continued work are given.

The operation of the pin pallet runaway escapement has been characterized in terms of several kinematic properties, i.e., velocity ratio, torque transfer ratio, and efficiency. A computer program has been written which analyzes both the entrance and exit phases of the engagement cycle. The influence of changes in the operating center distance has also been investigated by appropriate computer runs. As a result of this study, an analytic tool for the evaluation of the performance of proposed pin pallet escapement designs or for the modification of existing mechanisms is now available., Formerly ADE400374.

Computer simulations of complete safing and arming mechanisms containing pin pallet runway escapements, two- or three-pass involute gear trains and spin driven rotors were developed. The three motion regimes of the runaway escapement, i.e., coupled motion, free motion and impact, were included. In addition, the ability to consider the effects of pallets with arbitrarily located centers of mass has been introduced. Further, the contact forces of the gear trains and the escapement may be obtained. Simulation runs of actually existing mechanisms were made and good agreement with experimental data was obtained.