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The pay-off from higher power
Page 17
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• Raising the power-to-weight ratio of a goods vehicle from 5 bhp/ton to 6 bhp /ton saves an average of 78 min delay per 620 miles to following cars and 33 min to following lorries. This is one of the conclusions of a new Road Research Laboratory Report 1LR291I entitled "Social benefits from minimum power-to-weight ratios for goods vehicles".
The report goes on to show that a rise from 6 to 8 bhp/ton saves 53 min and 26 min respectively and from 8 bhp /ton to 10 bhp/ton saves 16 min and 8 min. The benefits to the community of raising the power-to-weight ratio of a single vehicle travelling 50,000 km 131,000 miles) in 1969 are assessed to be £56 for a rise from 5 to 6 bhp/ton, E40 for 6 to 8 bhp/ton and £11 for 8 to 10 bhp /ton.
To assess these benefits three artics were driven round 990 miles of main trunk routes in England, and the delay caused to other vehicles was measured. The tractive units were an Atkinson with 150 bhp Gardner engine, 6-speed gearbox and 6.28 axle ratio, running at 27.9 tons with a power-to-weight ratio of 5.36 bhp/ton; an Atkinson with a 180 bhp Gardner engine, 6-speed gearbox and 6.28 axle ratio, running at 27 tons and having a power-to-weight ratio of 6.67; and an AEC Mandator with 226 bhp AEC engine, 6-speed gearbox and 6.25 axle ratio, running at 23.2 tons gross to provide a 9.68 bhp/ton power-to-weight ratio.
In supplementary tests, using a turbocharged Leyland Beaver at 8.09 bhp /ton, speed and acceleration on hills were measured and compared.