ader Air7hydraulic Brakes Tested
Page 11
If you've noticed an error in this article please click here to report it so we can fix it.
lounced in our June 28 issue, in Thames Trader forwardand introl models are now available 'hydraulic brakes as optional It, this system adding £21 to the ssis prices. A tractive unit thus was made available for test esday, and the figures obtained an improvement in overall on in the order of 20 per cent
I with the results given by a tractive unit fitted with the vacuum-hydraulic brakes which
d last year.
at& tested this week consisted mdard Trader forward-control odd l with air-hydraulic brakes faskers 12-ton Soper Straight mu-trailer with full air brakes. live unit had Girling I6-in, by it brakes and I5-25-in. by 5-in. .kes, giving a frictional area q. in., actuated by a Clayton e type 36 brake chamber. The er had Girling 15.25-in. by 5-in. ng-shoe brakes, with a total area of 296 sq. in. and the outfit ssing 15 tons 17 cwt. (payload approximately 10 tons), giving 48.9 sq. in. per ton gross.
This frictional area per ton is 1-6 sq. in. less than the figure with the vehicle tested last year (August 10, 1962), because although the lining area is the same, the gross weight this time was 13.5 cwt. greater. Whereas last year's vehicle— which had a York semi-trailer--took 30 ft. to stop from 20 m.p.h. and 67 ft, from 30 m.p.h., the air-hydraulic combination required only 25 ft. to stop from 30 m.p.h. and 53-75 ft. from 30 m.p.h., without any wheel locking, and this at far lower pedal effort, too.
On this score alone the extra £21 is entirely justified, but fade resistance was proved to be slightly better also; the latest vehicle lost more than last year's, hut the final maximum-deceleration figure was 4 per cent higher after a 2.75-minute descent of 0.75-mile, I-in-10.5 hill. As before, tractive-unit handbrake performance was poor, with only 16.5 per cent being obtainable from 20 m.p.h., but the semi-trailer brakes alone gave 25 per cent when the hand reaction valve was
applied from this speed. J.F.M.