Following an introduction of general historic nature dealing with the evolution of the modern road roller from the first practicable steam roller of 100 years ago, the paper is confined generally to an examination of the mechanical engineering content and operational requirements of this item of engineering plant universally employed in today's surface consolidation, compaction and finishing processes. The mechanical constitution of the road roller is examined with particular reference to recent developments in design concerning clutches, mechanical, hydrokinetic and hydrostatic transmissions, steering, brakes, bearings and hydraulic systems, all of which are in close accord with modern automotive design practice. Curves illustrate the basic co-ordination requirements of engine/torque converter combination, the torque converter and hydrostatic unit output performance characteristics and vehicle road performance (gradient/ mile/h) with the mechanical ‘stepped’ transmission, the overlapping torque converter transmission and infinite ratio ‘stepless’ hydrostatic system. Additional equipment fitted to the roller for performing operations other than surface rolling is also considered together with features designed to produce maximum operational efficiency. Modern design trends to satisfy present-day demands of maximum machine utilization with minimum servicing and maintenance ‘down-times’ are considered with particular reference to lubrication and accessibility for servicing. Conclusions to past and present are given in the author's views on probable future trends in design and construction.
MODERN TRENDS OF DESIGN, RESEARCH AND USE OF HYDRAULIC MACHINES IN DRIVES OF MECHANISMS AND TRANSMISSIONS (REVIEW ARTICLE)