A world-leading manufacturer of agricultural machinery, including the global New Holland and Case IH brands, CNH demands great things of its hydraulic system supplier. Sauer-Danfoss lives up to expectations, most recently with the integrated brake function for combine harvesters and a new feeder drive stop block for forage harvesters.
Economical, lighter and more compact, a turbocharged seven-litre diesel engine is infinitely preferable to a traditional 10-litre engine used on large agricultural machinery in Europe. But one major drawback is the danger of excessive engine RPM due to reduced braking capability.
CNH became aware of the problem when designing its new generation of combine harvesters and contacted Sauer-Danfoss, already the supplier of the hydrostatic propel drive and steering unit, for a solution. The Sauer-Danfoss integrated brake function (IBF) was soon in development.
The problem of excessive engine RPM is a direct result of the limited braking torque of turbocharged diesel engines when used in heavy machinery. As braking capability is dependent on the volume of the engine, a reduction in engine size from 10 to seven litres has an impact. With excessive Engine RPM comes the risk of expensive damage to the diesel engine and other attached components.
Full braking power
The IBF is designed for use with Sauer-Danfoss Series 90 pumps. Comprised of a check valve, orifice and pilot-operated, pressure-reducing valve, it draws on the diesel engine's full braking power in every situation. This optimum performance is secured by the closure of the pressure-reducing valve at a braking pressure of about 20 MPa, equivalent to the diesel engine's braking capability. At the same time, the maximum braking pressure of 45 MPa is maintained across the motor. This not only prevents overheating of the hydraulic circuit but also eliminates the need for additional service brakes.
Today, CNH has successfully implemented the IBF on its combine harvesters. The solution is also broadly suitable for many other types of heavy-duty machinery.
Function integration
After more than 30 years of working with CNH, Sauer-Danfoss is well versed in the hydraulic needs of all the group's agricultural machinery. That includes the New Holland and Case IH ranges of forage harvesters, which are now equipped with a hydrostatic feeder drive stop block (FDSB) that combines a number of functions for improved flexibility, performance and a longer working life.
The FDSB enables machine operators to vary the speed of the feed rolls, and hence the cut length of forage, instantly and effortlessly from the cabin. An emergency stop function also brings the feeder to a halt in under 20 ms if metal is detected in the crop - for example, a small piece of fence wire is enough to cause severe damage to the knives if allowed to enter the cutter drum.
For cleaning purposes, the FDSB has a reverse function for easy removal of foreign objects or forage that has become stuck between the feed rolls. The FDSB is constructed as a manifold, comprised of a solenoid pilot valve, a stop valve with a bypass function and a pressure relief valve, which is bolted on the end cap of 75 and 100 cc Series 90 motors. If metal is detected, the solenoid pilot valve closes the outlet port of the hydraulic motor, while the stop valve prevents cavitation by maintaining oil flow to the pump. The relief valve guards against excessive pressure build up while the motor is shut off.
Altogether, the FDSB represents a compact and cost-efficient combination of functions on New Holland and Case IH forage harvesters. And that means fewer components and reduced maintenance requirements - responding to two more of today's popular market trends.
A global company committed to meeting global needs, CNH is fulfilling its mission with the new generation of combine harvesters and forage harvesters
For more information contact Sauer-Danfoss, +27 (0) 11 803 8390.
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version