Gulf Construction Online - ZF drives towards less noise, more power

Excavators

ZF drives towards less noise, more power

01 March 2004

ZF’s newly-developed range of axles and transmissions – precisely matched to one another – underlines the company’s system capabilities in mobile excavator applications.

“The new transmissions in the HL line – HL 250, HL 270 and HL 290 – replace the previous HL 70 and HL 100 and can be used in wheel excavators from 550 Nm to 950 Nm tractive torque,” says Jochen Weidemann, vice president marketing and public relations.
He says: “Apart from the increase in the power range and the reduction of the versions, the objectives of the ZF engineers included:
• A more compact installed size of the new drive system with standardised mounting points;
• Improvement of the gear-shift quality;
• Reduction of the noise level;
• Reduction and standardisation of the components;
• A standard brake design for the front and rear axles; and
• An increase in traction.
The new development has reduced the axle types from four to three and now covers all vehicle classes up to a service weight of 25 tonnes.

HL series of transmissions
With the new transmissions, the German automotive supplier of driveline and chassis technology is opening up higher versatility and significantly increased power ranges to modern wheel excavators. The new generation comprises three power classes, which are designed for the same installation. The maximum tractive torque for the transmission HL 250 is 520 Nm, 770 Nm for the HL 270 and 950 Nm for the HL 290, says Weidemann.
The transmissions are available in two variants of transmission ratio, matched to the transmission ratios of the new generation of axles. Optimum adaptation, greater gear-shift spacing for the transmission ratios and still better efficiency, enhance the driving performance of mobile construction machines. The transmission can be mounted separately on the chassis as well as directly on the ZF axle. The reduced installation size and standardised mounting points simplify installation, leading to more design freedom for the vehicle manufacturer, he says.
With the introduction of the internal lubricating oil intake method, the external oil line has been done away with.
Commenting further on the innovations made Weidemann continues: “Another point is the reduction of the noise level. Here, progress has been achieved partly by reducing the speed of the hydraulic motor.
“Apart from the transmission, ZF also supplies the valve block for the transmission control. This consists of a 4/3 directional control valve for the gearshift and a pressure protection valve with an integral pressure reduction function. In conjunction with this, there is also a protective function for the transmission and for the complete vehicle.
“For example, the parking brake is automatically activated when no gear is selected, the vehicle is shut down or the power supply fails.
The ZF Group, is a leading worldwide automotive supplier for driveline and chassis technology and has a total sales of over $11 billion (September 2003). The company has more than 53,000 employees at 119 locations in 25 countries and ranks 15 among international automotive suppliers, concludes Weidemann.