Building blocks

20 March 2008

The HC 85 hydrostatic transmission from ZF delivers speeds up to 42 km/h.

The HC 85 hydrostatic transmission from ZF delivers speeds up to 42 km/h.

Fundamentally, Components Create the motion and power that are the essence of construction equipment, and manufacturers of these assemblies have been busy improving their products. Let's look at power first.

Rexroth's new variable displacement pump, the A10VO series 53, gives equipment designers for the first time, says the company, the choice of hydraulic-mechanical power control or electro-proportional differential pressure control in a medium-duty axial piston pump.

Hydro-mechanical control of the lightweight, compact unit will be attractive, for example, to prevent engine overloading of wheeled loaders, in which benefits of robustness and cost effectiveness are paramount. Such power control also frees the operator from throttle setting and allows him to concentrate on controlling machine movements.

On the other hand, electro-proportional adjustment of the swivel angle of the slush plate provides precise control of flows and electronic limit controls. Such electrically-adjustable control of differential pressures in hydraulic circuits allows fine control of actuators, for example, and damping of cylinder end movements. The electronic nature of this control gives designers more flexibility and the owner upgrade potential.

The series 53 pumps, suitable for 250 to 315 bar applications, lay the groundwork for developing “intelligent”, fully electro-hydraulic systems, such as electro-hydraulic flow matching. This concept ensures sufficient flow in the system as a whole to meet varying demands from individual actuators and motors. Doing so improves system response to operator control changes, as well as reducing sensitivity to disturbances. Consequently, machine hydraulics “... are more agile and less sensitive to vibration,” states the company.

The benefits for operators from Sauer-Danfoss' new direct displacement control pump are increased machine life and lower noise levels, says the company. The pump's distinguishing characteristic is that its neutral return mechanism (the device that returns the swash plate to the neutral position), common in all pumps, is built-in. The location inside the pump ensures continuous lubrication and protects the mechanism from knocks, contaminants, and vibration.

Sauer-Danfoss says the pump, designed for closed loop applications in mini excavators, walk-behind skid steer loaders, and small tractors, for example, is -4 dB quieter than similar products.

Of direct benefit to OEMs is that the pump, available in 25, 30, and 35 cm3 displacements in a single-sized housing, is smaller and easier to install, because there are no external linkages and springs.

Linde Hydraulics has a new pump, too: the without an adapter. According to the company, the system is unique and makes on site repairs quicker and simpler.

A good example of functional flexibility comes from Poclain. Its new, 420 kg, MW 50 hydraulic motor offers both high displacement and high displacement ratio performance. That two-in-one capability provides efficient high-torque, low speed and high-speed drive of large-wheeled vehicles, such as loaders. The motor's three displacements allow three different traction/speed modes, while generating 140 kW.

The French company has also responded to OEM demand for increasingly compact components. Its MZ motor, targeting zero-tail swing mini-excavator slew drive applications, combines the functionality of open loop hydraulic circuits with closed-center valve operation. Its flange-mounted manifold block, available in two versions for 2 to 8 tonne and 8 to 18 tonne applications, provides improved braking control and reduced system feedback. The motor offers displacements from 172 to 2518 cm3per revolution and 250 bar pressure.

Drivetrain

Other manufacturers are more effectively transferring generated power to the work cycle. Dana offers its new Spicer four-speed, 800 Nm torque, HSR08 power shuttle transmission, for telehandlers with engines up to 88 kW. New, too, is the model 114 front axle, which completes the US-based company's range for 3 to 50 tonne front-end loaders.

For heavy-duty, off-road mining applications is Dana's Spicer Hercules 37R axle. It features a rigid, three-piece support, as well as “extra-capacity” wheel-end bearings and heavy section components to accommodate a wide range of payloads, tracks, tyres, and chain combinations.

ZF has a new hydrostatic transmission for equipment up to 9,5 tonnes: the HC 85. It provides continuously variable vehicle speeds up to 42 km/h and offers improved mechanical efficiencies, says the company, leading to fuel savings.

It has also created a new generation of its Ecomix CML 10 (Concrete Mixer Lowspeed) product range, for concrete mixers up to 10 m3 drum capacity and transferring an output torque up to 62000 Nm. The company says they are -50% shorter, -20% lighter, tougher, more flexible, quieter and easier to service.

New from Italy's Carraro is an integrated drive train with servo synchro transmission for backhoe loaders. It consists of a 26.22 front axle, the TLB1 servo synchro transmission and a 28.48 rear axle. According to Carraro, the TLB1 offers significant advantages over a power shift transmission, including reduced power loss and a simplified architecture: less components, less complex parts, easier installation, and its TRAX electronic control unit.

The Italian company also has a new, F1300 final drive for 600 tonne class mining excavators. It benefits from high-capacity taper roller bearings, improved gear grinding, advanced heat treatment and the use of ductile steel.

Brevini of Italy offers new right-angle gear units for excavator equipment in ratios from 1:75 to 1:660 and power capacities up to 950 kW. The “high power” line combines the performance of its S series planetary gearboxes with the reliability of its Posired series right-angle gearboxes, says the company.

Control Systems

Power and motion must be controlled, of course, and components manufacturers are improving both the precision and flexibility of their offerings.

Rexroth, for example, now allows the replacement of pressure control loops in conventional flow-sharing hydraulic (LUDV) circuits. Its new electro-hydraulic flow matching (EFM) control system generates a signal to adjust pump output at the same time it sends signals to valves. This change in control system concept makes the pump an electro-hydraulic variable displacement pump, not a device in a pressure control loop.

Prolec's new machine control system, the Digmaster Pro, features a graphical user interface and allows use of digital terrain maps (DTM) in different file formats.

The company's ProJob software converts DTM files into Prolec's proprietary .tri format, which are downloaded via USB memory stick into the on-board computer.

The operator can select from a number of different views and camera options, and the auto zoom feature displays the track of the bucket to target line.

Elsewhere, use of the Prolec's pcX-3D controller has been extended to drilling and piling applications. Also an extension, its Liftwatch 5, from the motion control range, has been applied for Kocurek's range of demolition and long-reach excavators to monitor operating envelope use.

Saurer Danfoss' latest version of its GUIDE software, which supports its Plus+1 range of micro controllers, input/output modules, and components, “makes it easier than ever for customers to develop complex control solutions, display and service tools for electro-hydraulic systems, “said Fred Bezat, the company's application software product portfolio manager.

The company has added, since the product's introduction at Intermat in 2000, blocks of software, tested and optimised for products in the range, which make it easier for OEM engineers to add and integrate units to their designs.

One example is the use of a modular toolbox that allows OEM programmers to choose data to be shown on individual service screens for calibrating control systems for control system development, production, or maintenance tasks.

Using software to control components for optimal performance, too, is ZF.

One product of ZF's efforts is its Ergolockup feature, an option that regulates the torque converter lockup clutch during low speeds to reduce fuel consumption of wheeled loaders, up to -15%, says the company.

It has also developed a new differential locking system that engages whenever the differential is not interfering to protect driveline components and tyres. The feature, available as Ergotraction, provides fuel efficiencies, as well.

Lastly, ZF's Ecotraction feature automatically disconnects four-wheel-drives at the transmission under detected, appropriate conditions, such as disconnection of one axle.

Linde's new LinDiag software allows easy set-up and fast diagnostics of its CED and CEB electronic control units for drives in both closed-loop and open-loop applications. Using the software optimises the drive system, while the ‘teach-in-function' matches Linde's system components - joystick, pedal, diesel engine, hydraulic pump and motor.

Poclain says its electronic control system for hydrostatic transmissions, SmartDrive Easy, helps meet Stage IIIA emissions standards. Using CAN-bus to link engine and pump, it controls the engine and pump displacement to provide automotive style driving, speed regulation, and braking assistance. Other benefits, says the company, include reduced fuel consumption and noise, acceleration and deceleration control, power limitation, and anti-stall.

The latest contribution to better equipment control from Michelin in France is an electronic system to measure tyre temperature and pressure in real time. A transceiver in the tyre sends that information to a cab unit, which can pass it on via GPRS.

Axiomatic's valve controller, the AX021300, exemplifies the trend toward flexible, integrated hydraulic components. Designed for either CANopen or SAE J1939 networks to control six on/off valves, embedded software provides functional and signal characteristics diversity across its two analog and three digital inputs and its outputs. Diagnostic capability includes storing actual current draw from solenoids.

Display

Flexibitility, too, is one benefit of new display units, and dashboards may become a thing of the past. Rexroth's 640 x 480 pixel, colour, high-resolution BODAS D13 unit displays any available vehicle information, including dynamic data from tachometers, for example. It can be programmed with the Windows-based BODAS-DCT (Display Configuration Tool) to design screens, context menus, and graphical elements. The device has an interface for overlaying input video images.

The D13 is a diagnosis and parameterisation tool, as well, when used together with other units from the BODAS modular system. Such use makes it unnecessary to connect a PC-based tool for service.

Sauer-Danfoss' new information display product is the DP200 Series graphical terminal. It presents engine, hydraulic, and machine performance data in a mono-chrome, back-light display unit, and operators can choose from four different configurations.

The unit has an optional USB port for connecting a PC to a machine's CAN network, providing a gateway for measuring performance, diagnosing faults and adjusting parameters. Analogue or digital inputs can be fitted for sending and receiving signals from sensors not connected to the CAN network.

The DP200 comes with Sauer-Danfoss' J1939 software package or as a PLUS+1 Compliant version, which is programmable using its PLUS+1 GUIDE software.

Material Technology

It is not just big, complex components that have received development attention. SKF's new bearing range uses a new material, called Hi-TF, and a new heat treatment technology, to create bearings with longer services lives, even under contaminated lubrication conditions.

SKF has also introduced a substitute for the bronze or steel bushes on either side of axle pivot joints, commonly used on backhoe loaders and tractors to keep wheels on the ground and a high-maintenance item because of high loadings, exposure to contaminants, and poor accessibility.

The bushes are made from high strength polymer and reinforced polytetrafluoroethylene (PTFE) fibres, which are self-lubricating, interwoven, and embedded in epoxy. The shaped, bonded assemblies are enclosed in glass fibre shells and have especially-produced SKF polyurethane wiper seals and steel cases to protect them from contamination and the axle shaft from corrosion.

The bush and seal combinations tolerate misalignment and vibration, are unaffected by edge loading and will not corrode. They do not need additional lubrication and are sealed for life.

For components that do need lubricating comes Groeneveld's new OnePlus product, an automatic, 2-grease greasing system for mini- and mid-sized equipment. Its electric plunger pump, electronics, and reservoir are in one housing.

Small but providing valuable information is the HYDACLac sensor, from Germany's Hydac. The device monitors oil conditions of viscosity, temperature, humidity, and dielectric constant and outputs analog or (alarm) digital signals.

Vibration Elimination

The purpose of some components is to isolate equipment operators from the effects of power and motion.

To that end, Sears' new Vibration Elimination System (VES) seat measures vibration and controls a damping mechanism in its air-suspension seat to minimise the passed on effects. A built-in computer integrates accelerometer inputs with seat position measurements to calculate commands to a valve in the electro-hydraulic dampening unit. The US company says vibration reduction is to below 0,5 Hz.

Elsewhere the VRS Semi-Active Seat, magnetic dampening technology from the Lord Corporation, instead of electro-hydraulics, dampens measured vibration in an air spring system.

Measuring and tracking vibration experienced by operators is the function of the VMS (vibration monitoring system), also from Sears. It is a seat, with built-in sensors, that displays instantaneous values in real time and records for later download accumulated vibration measurements.

The seat can be configured to record and store vibrations though its armrests, as well as through control devices, using an acceleration sensor on the operator's wrist. Mating with a storage device, such as a USB stick or a magnetic card, unique to individual operators, allows tracking of cumulative exposure as they move across machines.

Grammer is also helping isolate operators from vibration, offering two new seats with integrated controls. At the upper end is its Actimo Evolution, which comes in two versions: one for loaders and dump trucks, and another for excavators. Both versions' controls provide tactile feedback and are arranged in two levels; those more frequently used are at the top of the control stick. The seat automatically adjusts itself to driver weight and position, and it incorporates a low-natural-frequency suspension system to dampen vibration.

The MSG97EAC/742 looks similar to the Evolution model, but it includes an electronic system that dynamically adjusts the seat's pneumatic suspension to further reduce vibration transmitted to the operator.

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