The Arens Controls shift-by-wire system shown on an Allison LCT transmission unit.
Off-highway engineers work hard to provide comfort, ease of operation, and reliability to users. As an added challenge, they must design for operators who can spend an entire day working hard in their cab.
by Jean L. Broge, Editor
Like all other forms of mobility, off-highway equipment has become more technologically sophisticated to provide users with increased efficiency, productivity, and simplified operations. The increased use of electronics for engine control, transmission operation, and load-sensing hydraulic functions has resulted in greater accuracy and improved equipment reliability.
Electromechanical controls
Key among the growing use of electronics is the progression of electromechanical controls. Electromechanical technology continues to evolve and has become more advanced, especially in the area of electronic shift systems. While equipment manufacturers have incorporated electronics in a variety of ways, one area that remains to be fully explored is the traditional use of cables and push-pull controls to actuate various components in conjunction with electronics.
The Arens Controls shift-by-wire system shown on an Allison LCT transmission unit. |
Preparing to fill that development niche is Arens Controls Co., LLC, an Evanston, IL-based supplier of mechanical and custom electromechanical control systems, electronic shift selectors, input devices, actuators, and display assemblies. The company has developed, and is now testing, a shift-by-wire system for Allison Transmissions' light- and medium-duty commercial 1000, 2000/2400 series units that can be adapted to many off-highway-equipment systems. According to Arens, the development of the shift-by-wire technology was motivated by the need for better control, improved system monitoring, reduced maintenance, and simplified installation at the point-of-assembly not currently possible with traditional push-pull cables now in use.
The system developed for the Allison transmissions consists of a shift selector, interface module, actuator control module, neutral safety back-up devices, and a combination position sensor and actuator unit. Principal to the system is the interface module, which can be made to accommodate push-button, lever, or column-shift arrangements. It can also include J1587 or CAN output for display and diagnostics. Safety features can be programmed to prevent unwanted results such as equipment being driven if an attachment or implement is not secured properly.
 Arens Controls used a minimum number of components in its shift-by-wire system to enable a quick and simple installation. |
"The actuator can provide a precise shift from park position to drive in approximately one-third of a second and gear-to-gear shifting in about an eighth of a second," said Jim Hoadley, Vice President of Sales for Arens. Depending on the off-highway application, variations in software could allow more discrete positions or an infinitely variable system for specialized functions.
Hoadley cites simplified installation as an advantage of the Arens shift-by-wire system. "You simply bolt it up to the transmission and plug-in the connectors," he said. "There are no cables or linkages to wear and maintain." Hoadley added that long cables offer poor resolution at the output end, with significant reductions in efficiency over their life, leading to increased operator effort.
 AB Electronic's pedal position sensor replaces conventional throttle linkages and cables by transmitting the operator's pedal inputs to the engine electrically rather than mechanically. |
Sensor manufacturer AB Electronic has developed two accelerator-pedal-position sensor modules for electronic throttle control (ETC) systems. Designed for integration with plastic accelerator pedals, the thick-film, conductive-plastic inks and wiper-design position sensors are available for both angular- and linear-sensing applications. In ETC systems, an electronic pedal position sensor replaces conventional throttle linkages and cables by transmitting the driver's pedal inputs to the engine electrically rather than mechanically, reducing cost and weight in the overall vehicle. ETC systems also allow the integration of sophisticated computer control functions into the accelerator pedal assembly, including switch outputs for idle and/or a wide-open-throttle (or kick-down) positions.
The first sensor module of this type developed was the angular (or rotary) sensor for the UK-based pedal manufacturer Birkbys Plastics Ltd. Integrated into the end of the pedal beam, the sensor assembly is capable of detecting up to 27° mechanical and 22° electrical angles. The module also features an integral multi-way connector to provide signal output from the sensor to the throttle control computer. The second assembly was developed as a linear sensor module and integrated into a customer's molded pedal housing. The sensor measures linear motion up to 10 mm (0.40 in) and features a multifunction substrate with molded-in connection tags that form part of the sensor module's connector.
 The electrical output of Williams Controls' new WM528 electronic foot pedal assembly can be modified to meet specific system requirements.  |
Both sensor module designs are position-adjustable on installation, enabling the pedal's idle position to be set at the customer's specified output voltage. The sensor elements feature either twin- or triple-track outputs, with at least two different output laws.
For severe conditions in which drive-by-wire, foot-pedal control is preferred, Williams Controls - a designer, manufacturer, and integrator of sensors, systems, and controls for the transportation industry - has introduced a new electronic foot pedal assembly, the WM528. The company claims it is the first pedal on the market designed specifically for material handling equipment and other industrial applications. The assembly is mounted flush with the floor, with all of the electrical components located beneath the mounting surface. Primary structural components in the low-profile pedal are made of glass-reinforced nylon for heightened strength and impact and corrosion resistance. All the steel components are either stainless steel or plated.
The pedal was designed with several electronic profiles to make it compatible with the electrical requirements of most engines and electronic control units. The WM528 is rated for 0.05 W and requires a supply voltage of 0-5 V dc. According to Williams Controls, the pedal assembly requires no lubrication or routine maintenance and has been tested to 10 million cycles.
