Patent Application
20080198686
This invention relates generally to power systems for turning concrete truck drums, and more specifically concerns an engine-driven power system for use with small-load concrete truck drums.
Large concrete delivery trucks with rotating (spinning) drums which can accommodate 9-11 yards or even more of concrete are well known. In operation, it is important that the drum be kept spinning, regardless of whether the truck is moving or at a standstill. This maintains the concrete within the drum in a desired mix state.
In order to accomplish this, power for the spinning drum on the large concrete trucks is taken from the engine flywheel. In this arrangement, the drum continues to spin as long as the engine is running.
Small-load concrete trucks, e.g. those trucks having a 2-5 cubic yard capacity, also have used flywheel take-off systems to provide power for spinning of the drum. However, this arrangement has some disadvantages for smaller or medium-sized commercial trucks which are not specifically manufactured to carry concrete drums. Hence, it is desirable for a concrete truck with a small load drum to have a power system which does not use the engine flywheel and which spins the concrete drum as long as the engine is running.
Accordingly, the present embodiment is a power system for turning a drum on a concrete mixer truck, comprising: a power take-off unit connected to a power take off gear in a transmission for the concrete mixer truck, wherein the power take-off gear is driven by the engine, so that it is always operating, driving the power take-off unit, when the engine is running, regardless of whether the transmission is engage or not; a hydraulic pump powered by the power take-off unit; and hydraulic lines connecting the pump to a fluid reservoir and to a drive system for a mixing drum on the truck, wherein the mixing drum is capable of receiving a load of concrete in the range of only two to five cubic yards, wherein the mixing drum continues to turn as long as the engine of the truck is running.
Referring to
Two hydraulic lines 30 and 32 extend between the pump 24 and the planetary drive 14, for controlling the planetary drive 14. This is a conventional arrangement for concrete mixer trucks. Fluid can flow in both directions through lines 30 and 32, so that drum 12 can be turned in both rotational directions. Conventional controls on the pump permit an operator to control the direction of the fluid and hence the direction of the spinning of the drum.
Two additional hydraulic lines 34 and 36 extend between pump 24 and a fluid reservoir 38, one line carrying fluid from the pump to the reservoir and the other carrying fluid from the reservoir back to the pump.
In operation, mixer drum 12 will be continuously turning in one direction or the other as long as the engine of the truck is running. The mixer drum will continue to turn even through the truck may be stopped. This has the advantage of maintaining the concrete in a proper mix state. At a construction site, a discharge assembly 44, mounted to the rear of the truck 10, directs concrete exiting from drum 12 down a chute portion of the discharge assembly to the desired location for the concrete.
While the embodiment shown includes a connecting drive line between the PTO 20 and the pump 24, the pump can alternatively be mounted directly to the output port of the PTO.
The system shown and described herein is advantageous, since it provides a constantly turning drum capability for a concrete truck carrying small loads, i.e. two to five cubic yards, without requiring an engine flywheel take off assembly. Hence, a conventional medium or even light truck can be used, with a proper transmission, to carry a small/light size concrete drum.
Although a preferred embodiment of the invention has been disclosed for purposes of illustration, it should be understood that various changes, modifications and substitutions may be incorporated in the embodiment without departing from the spirit of the invention which is defined by the claims which follow.
