Spraying 2,000 Gallons of Tar
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A2,000-GALLON tar sprayer, converted by the Municipal Appliances Co., Ltd., Bamber Bridge, near Preston, from an cx-W.D. Leyland Hippo sixwheeler, has been delivered to R. J. Maxwell and Son, Ltd., Coleraine, Northern Ireland. The machine can spread a 7-ft. 6-in, wide carpet of tar 0.043 in. deep at the rate of 4,400 yds. an hour. It tows a 5-ton gritter for the application of sand, gravel or chippings.
The vehicle has a modern Leyland cab, a 13-ft. 6-in, long elliptical tank and a separate compartment housing an auxiliary oil engine, compressor and reservoir, and a 40-gallon fuel-oil storage tank for feeding two oil burners to heat the bitumen in the main tank. Its unladen weight is just over 12 tons.
By means of a three-way valve, bitumen is loaded into the tank by the pump used for spraying. Firing tubes of 10-in, diameter run from two rearmounted oil burners along the full length of the tank and heat the bitumen at the rate of 100 degrees F. an hour. A 11-in. thick Fibreglass mattress, sandwiched between the tank walls, maintains the heat with an hourly loss of only 11 degrees with this system, fuel costs for heating the bitumen work outat 0.066d. a gallon an hour.
Bitumen is expelled from the tank by a 21-ia, rotary pump, mounted inside the tank and driven by the auxiliary engine. It is capable of delivering 70 gallons of bitumen a minute, which is in excess of maximum working requirements. The spray bar, mounted about 2 ft. above ground level at the rear of the machine, carries 11 distributing nozzles which are opened sir,nultaneously by a master lever.
To enable the driver to maintain a constant speed to give an even rate of spread, the Hippo has a separate wheel to drive the tachometer, which has a 6-in, dial and is calibrated from 0-5