Date of Award


Document Type

Master Thesis

Degree Name

Master of Engineering (Research)


Mechanical and Automotive Engineering

First Advisor

Dr. K. McMullen


This project involves the measurement and simulation of the dynamic performance of a pushrod valvetrain, in particular that of the outer valve spring. The engine was donated by S&S Cycle Wisconsin. A motoring test rig was constructed to obtain high speed camera footage of the spring coils motion. Individual static spring coil displacement measurements were taken, and their stiffness studied. Spring and pushrod natural resonant frequencies were measured. All data acquisition and analysis was carried out with Labview programs written during the project. Programs were written to model individual static coil stiffness using the close coil, open coil, and theories by Wu and Hsu [16]. Both linear and lumped parameter models were written to model the springs dynamic performance. The entire valvetrains dynamic performance was modelled in 4stHEAD, which is a software suite produced by Prof Blair and Associates [4]. The spring stiffness, spring frequency, and coil stiffness results are examined in detail with measurements, 4stHEAD simulation results, and results from the author’s programs where applicable. An in depth analysis of the 4stHEAD simulated dynamic valve lift, with particular emphasis on damping constants was carried out. The dynamic coil displacement, from measured results, 4stHEAD simulated results and results from the authors programs are examined in detail, with particular emphases on transient vibration amplitude and frequency. The possibility of carrying out further work is discussed.

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