GB1417049A - Concrete mixing - Google Patents

Abstract

1417049 Rotary drum mixers H L MORGENSTERN 26 April 1973 19922/73 Heading B1F [Also in Divisions B7 and B8] In a method of transporting concrete ingredients to a job site and mixing it, the cement for a batch is transported separately in a trailer drawn behind the mixing truck and is pneumatically conveyed into contact with the other ingredients within the mixing drum using a low pressure air supply. The trailer may also convey the ingredients for one or more further batches. An apparatus comprises a mixing truck 1 towing a trailer 2 having hoppers 13, 14, 15 for cement, 16, 17 for aggregate, and tanks 18, 19, 20 for water, all except the tank 20 containing premeasured quantities. Water and aggregate for the initial batch are filled into the mixing drum at the batching plant; on arrival at the job site cement is added by a pneumatic conveyer 22, and distributed in the mix, by low-pressure air (7-10 p.s.i.) provided by an engine-exhaust blower 7. After the first batch is discharged the aggregate and water for a further batch may be supplied to the drum by a belt conveyer 35 and hose (53, Fig. 5 not shown). The low pressure air is also used to fluidize the cement hoppers and to provide top pressure to them and to the water tanks to assist discharge (see Fig. 3, not shown). High pressure air (100-110 p.s.i.) from the vehicle braking system is used to operate vibrators (30) associated with the cement and aggregate hoppers and actuate the various gates and valves (see Fig. 4, not shown). A hydraulic pump 5 supplies power to the belt-conveyer 35 and for raising and lowering the trailer draw-bar 10.