Analys och utveckling av boggi till ramstyrd dumper

Sammanfattning

Volvo Construction Equipment is one of the worlds largest manufacturer of heavy

machinery. In Braås, Sweden, they develop and manufacture articulated haulers in

several sizes. The biggest, the A40, is capable of loading almost 40 metric tonnes.

These haulers have a bogie to distribute the forces of the load evenly onto the two axles

and there wheels. The bogie is constructed using a rigid balance beam on each side of

the frame connecting the axles or an independent solution using hydropneumatics.

An analysis has been made in order to establish the forces created during cornering

and through the theory, an estimation of the extensive tyre wear and extra fuel

consumption has been made. All due to the effects of the tyres not being inline with the

cornering radius. Instead the wheels are turning around a point in the extension of the

bogie center.

Three ideas of concepts has been suggested and evaluated and two of these ideas has

shown great potential in solving the problem satisfactory. The main feature of the ideas

are to either control the entire rear bogie axle or to control the rear wheels

independently. Both solutions make use for hydraulic motors instead of conventional

driveshafts. It will provide sufficient power in low speeds and has small deficiencies

during higher speeeds.

In the analysis a driving cycle is produced from driving a hauler on a test ground. It

shows that barely 5% of steering angles are above 30 degrees. From this driving cycle

and from the theory a net savings of 141000 SEK are made calculating a 10% decrease

in tyre wear and a 1% decrease in fuel consumption throughout a 12000 hour session.

This sum is to be divided between machine owner, retailer, Volvo CE and potentially

increased production cost.