When it comes to pumps and motors, equipment designers have plenty to choose from. The ability to direct energy throughout a machine in neatly packaged systems has given designers the freedom to create machines that best fit the intended function.
Helping make that decision are the product managers at the various component suppliers. In this issue, we look at a few examples of where expert help provided solutions for equipment manufacturers.
|In the closed center variant of DanTruck's
new lift truck, the Denmark-based manufacturer
uses a Bosch Rexroth axial piston variable displacement pump with a particularly low noise level. © Rexroth
From an Inquiry to a System Partnership
edited by OEM Off-Highway
DanTruck A/S of Uldum, Denmark, a builder of forklift trucks with a capacity of up to 9 tons, recently revised one series of its trucks with the latest in mobile hydraulics and electronics.
We had actually inquired about prices from various manufacturers about hydraulic components, in order to reduce the manufacturing costs of our 9000 Series," says Morten Gregersen, development manager, DanTruck. The company supplies three series of forklift trucks for handling loads between 4 and 9 tons.
Bosch Rexroth application engineers suggested a new approach, in which DanTruck could not only reduce costs, but also gain more flexibility for customized solutions.
Rexroth and DanTruck worked on a profile where requirements, wishes and a few new ideas flowed together. The result: a system solution for the working hydraulics, the steering equipment and the brakes, as well as the fan drive for the diesel engine. The system consists of the control block M4-12/15 with load sensing, with the pressure and volume flow matching the immediate requirements of one or more users.
In the forklift model with an open-center hydraulic system, DanTruck integrates the Rexroth Silence external gear pump, known for its low volumetric flow pulsation, one of the major sources of noise from this type of pump. An axial piston variable displacement pump supplies the oil flow in the closed-center variant of the truck. In both, the goal of DanTruck to build the quietest forklift trucks of their class are supported by the pumps.
The variable displacement version also reduces fuel consumption. As well as the machine's actual working hydraulics, the pumps supply external equipment through programmed functions. "We are moving the changes from the hardware into the software," says Gregersen. "In this way we can react to the customers' wishes after delivery."
Small Steering Motor
by Chad Elmore
For years, Poclain Hydraulics has offered a range of hydraulic motors for steering wheels. Models from its MG Series have been popular on the rear axles of combines as well as other applications in large equipment. When a German manufacturer asked for a smaller wheel motor that could be used to steer its compact equipment, Poclain engineers got to work.
"The main challenge with this development was to make a compact product," says Jean-Marie Perret, marketing manager - North America, Sturtevant, WI. "But it also had to be robust to comply with extremely demanding specifications."
Recently introduced, the lightweight MG02 motor can shorten the turning radius of machines compared standard steering axles or articulation, thanks to its swivel angle. The MG02 also allows for design flexibility and machine stability.
"In an articulated machine, the steering angle is defined by the machine's pivot joint," says Perret. "Stability also limits the steering angle. When steering, the center of gravity moves toward the machine's outside and creates a risk of instability.
"MG02 motors help a machine maintain its center of gravity, even during a tight turn."
|H1 motor © Sauer-Danfoss|
A Common Goal
by Chad Elmore
Sauer-Danfoss' diverse component range is featured in its advertisements, catalogs and a recently redesigned website. However, the nature of the business means that finding the right part for a specific application often requires a phone call.
When an engineer from an OEM is on the other end of the phone line, some of them are aware of the Sauer-Danfoss product portfolio, "but it has become so extensive over the last 10 years, they can't know everything in technical detail," says Jim Eisenmenger, applications engineer, Sauer-Danfoss. "When they call they are looking for our technical recommendation as to what will solve their particular problem."
During that conversation, the test data collected by the OEM and Sauer-Danfoss becomes valuable. "It is our eyes and ears for what is going on in the machine," says Eisenmenger. "They are counting on Sauer-Danfoss to help solve problems because we know our product line extensively."
These days, vehicle design teams are expected to accomplish more with fewer resources. They work in smaller teams while getting to market faster. Likewise, tomorrow's vehicles will require a higher level of vehicle management and electronics, improved productivity and ease of operation. "Here's where we can really help design teams excel," notes Eisenmenger.
Simply selecting a part number and filling out an order for a dozen pumps would be easy. Easy — but ultimately not a big help to the customer, because each application is different.
"We have positioned ourselves to provide solutions, not just products," says Rob Arndt, product portfolio manager, Sauer-Danfoss, Ames, IA. From account manager to applications engineer to product manager, the Sauer-Danfoss team works closely with customers to develop optimized vehicle systems and to verify that performance characteristics have been met.
This group was recently called upon to solve a situation an aerial lift manufacturer was having with one of its pumps. Its customers were experiencing premature failures to the aluminum pump installed in the machine.
Field testing showed cold weather start-ups resulted in peak pressures several hundred psi higher than the pump's rating. "But if you only looked at the schematic, the pump looked like the right choice for the application," says Eisenmenger.
Sauer-Danfoss recommended its D Series pump, featuring ductile cast iron housing and a design known to be durable in high pressures.
Selecting the D Series saved the OEM time, with 3D models available in a couple of days, and a prototype part available within just two weeks. Because the pump is designed in modules, specific configurations could be quickly assembled and keyed into the system.
There was another benefit, too. "Due to the robust reputation of the D Series pump, the customer decided to eliminate their typical high-pressure cyclic
endurance test and only run their pulse test to qualify the application," says Arndt. "This saved their program time and money."
When OEMs run into problems with their machine, Sauer-Danfoss helps them solve those problems quickly with the team approach. One of the outcomes of working as a team is selecting a product that is priced appropriately and one that will help avoid warranty discussions.
"The challenge is in selecting a product to meet the OEM's life expectation for the machine," says Jeff Sipila, account manager, Sauer-Danfoss, "but not exceed it by too much. Finding the right solution is our priority as we partner with customers. We could put a D Series pump on everything, but it's not always necessary."
New family member
Bent axis motors are the most recent addition to the H1 family.
Sauer-Danfoss recently added bent axis motors to its H1 family. A key feature of the new H1 motors is their zero-degree capability.
The ability to seamlessly reduce the angle to zero degrees means there is no torque interruption, or sudden change in speed when switching from, for example, work range to travel range. This enhanced control is precise and also improves the feel of the system during operation.
"Zero degree capability enables OEMs to provide additional features," says Hans-Peter Nissen, product portfolio manager, "including accurate anti-slip and torque control functions, which increase vehicle productivity and optimize power utilization."
Bucher Hydraulics Inc.