The internal dimensions shown to the left and right in Fig. 1 are identical and were directly measured at the local concrete premixing plant: the internals consists of two helix shaped blades, in which the blade thickness is roughly 8 mm, while the height is about 430 mm. The space between two adjacent blades is 620 mm on the average. As shown in Fig. 1, all these numbers vary as a function of the location within the drum. These number also change as a function of time, depending on drum usage. That is, the concrete wears and tears the internals of the drum with time.
Decrease of availability of fossil fuels and environment issues, push research towards the development of high efficiency power trains for vehicles that transport people, goods and mobile operating machines, like the concrete 5cbm mixer truck considered in this paper. Conventional concrete 3cbm mixer truck use diesel engine to move the truck and a hydraulic system which keep spinning the concrete drum. A hybrid powertrain based on battery-powered electrical drives can replace the conventional hydraulic system assuring an efficiency improvement. Furthermore, thanks to the reversibility of the electrical drives, it is possible to recover kinetic energy during the braking phases of the truck. Aim of this paper is to study and develop a hybrid powertrain for the concrete mixer drum. The study is based on a full energetic model of the vehicle developed for sizing the components and designing the control strategies. A model of the conventional hydraulic 8cbm mixer truck has also been proposed in order to evaluate the benefit introduced by the proposed hybrid system. Simulation models have been validated comparing experimental data collected on a conventional mixer truck in different operating conditions.
Most construction equipment is easy to understand. Cranes move things up and down. Dump trucks load up, move out and unload. Bulldozers push and graders grade. The one exception to this is the humble cement mixer, beloved by children, hated by in-a-hurry drivers, and misunderstood by most people outside the cab of the 30,000-pound (13,608-kilogram) behemoths.
While concrete has been around in one form or another since before the Romans built the Appian Way, the transit mixer is a child of the 20th century. But recent invention or not, the mixer is here to stay.