In recognition of his outstanding contribution to tribology research, application and teaching.
Professor Blok is renowned for his work across the spectrum of friction, wear and lubrication, in particular for his discoveries and explanation of tribological phenomena and for their display in a form readily usable by designers. He has excelled in applying his academic work, and that of others, to the solution or urgent problems encountered in the practice of mechanical engineering.
After graduating from the Delft Technical High School, and a short period as research assistant, Harmen Blok joined the Delft Laboratory of the Royal Dutch Shell Group in the early 1930’s, to work on the fundamentals of lubrication; few can ever have been better suited to this task. He left this company in 1951 to continue a life dedicated to Tribology as Professor of Mechanical Engineering at his old school, now the Technical University of Delft.
One of his first duties at the Delft Laboratory was the development, with the late Professor Boerlage, of the famous and ubiquitous Four Ball EP tester – now in world use – and particularly the establishment of test criteria for it, which would best relate to practice. In addition, the IAE Gear Rig, the first of the standardised gear rigs, was developed from a slightly smaller rig which Blok had also developed during this period.
Blok’s suggestion, first advanced in two brilliant papers in 1937, of the constancy of the total transient temperature at scuffing, has rightly been called one of the most “germinal ideas in the history of lubrication”.
Though some experiments have often confirmed this postulate, others have not, or have not appeared to do so and Blok has zealously pursued the significance of these results and exposed, in papers and conferences all over the world, the variety of factors playing their part in the phenomenon and their complex interactions.
Providing, as it does, an insight into the phenomena of rubbing contacts, his work has had a profound influence on the understanding of the behaviour of gear teeth and on the design of gears, particularly the latter, for Professor Blok has always approached his subject as an engineer and has striven to provide data of use to the designer.
As a necessary complement to the estimation of the “flash-temperature rise”, Blok has devoted much effort to means of calculating the steady temperatures of gear blanks by developing his “thermal network method”, and by studying the dissipation of heat from gear transmissions. More recently he has established the maximum rate of cooling possible with the spray method of supplying oil to gear teeth and has suggested ways of improving their rate of cooling.
Another powerful tool for the design engineer was his development of the Mobility Chart and Impulse Capacity Methods for analysing the performance of dynamically loaded plain bearings. In the subject of wear, many of the present studies of asperity interaction stem from early work by Blok on the conditions under which the surface asperities became flattened either elastically or plastically. Another aspect of his many sided contributions has been in viscometry and rheology of lubricants. With others, he developed the Slope Index or Dynamic Viscosity Index which, for the first time, enables high density and low density lubricants as well as low viscosity and high viscosity lubricants to be compared in respect of viscosity/temperature properties.
In all his work, Blok has sought for the underlying physical truth behind tribological subjects of engineering importance, using his great powers of mathematical analysis, particularly dimensional analysis. In his studies of hydrodynamic lubrication, especially of the “foil bearing” now being used in some modern electronic computers, and of the “inverse hydrodynamic theory” which he developed in that connection, he foreshadowed the elasto-hydrodynamic theory” of gear and roller bearing lubrication.
Professor Blok’s work has been published in hundreds of papers and powerfully and felicitously adapted to the finest nuances of the complex subject of tribology.
His contribution to symposia and conferences, both in Europe and America, must be almost unequalled. Indeed, there are few major conferences on tribology, if any, that have not benefited by some contribution from Professor Blok.
Professor Blok is a man who has devoted the whole of his 40 years of professional life to tribology and who has been immensely successful in his endeavours. His known generosity in making available his knowledge to others – especially to new generations of tribologists – is likely to benefit engineering for many years to come.