Wood chippers get sophisticated

Product Design & Development; 4/1/2006; Vermillion, Len


A wood chipper might not seem like that most sophisticated type of equipment. These outdoor power machines generally perform basic functions. Their main task is simply to clear brush and to turn vegetation into mulch. But handling shrubbery, branches, and small trees requires more sophisticated components than one might think.

One of the largest manufacturers of wood chippers is Rayco Manufacturing Inc. The Wooster, OH-based company manufactures a variety of wood chipper models, including the recently released 80 HP RC-12. The company has a growing of environmental equipment ranging from the 25 HP RC 6C model to the heavy-duty 225 HP RC 20xp. With all of its equipment, Rayco has worked to offer enhancements that will give users better machine performance, greater safety, fuel savings, and future operation upgrades.

In order to accomplish its improvement goals, Rayco sought to use microelectronics in its new designs. To help, the company turned to HED Inc., which provided a microprocessor-based electronic module to coordinate both engine functions along with that of the feed/cutting system. Called the CL-410, the module is part of HED's CANLink family of modules.

Rayco chippers grind wood using "knives" attached to rotors. These parts are ground to finish dimensions with a 1/1,000-in. tolerance. Rotating at high speeds of over 2,000 rpm, the machine takes in shrubs, branches, and trunks at a rate just under 150 ft/min.

A single CL-410 module monitors and controls operation of the throttle and the chipper's feed mechanism. Various clutch-engagement and fuel-saver parameters trigger the module's control of the engine throttle. Using fault codes from the ECU on machines with engines with more than 100 hp, the system can perform a machine shutdown if the feed mechanism becomes jammed. Rayco wanted to have this capability as it developed its product line.

Upgraded Electrical System

Thinking ahead, Rayco knew it would be eventually moving into Tier II engines, which would call for the higher amperage outputs this module handles. The CL-410 module offers protected input/output circuitry that can withstand spikes and shorts in the wiring.

The module has more than enough connector pins to meet needs of the wood chipper functions that include cutting speed, fuel controls, the braking system, and indicator lights. Originally developed for Rayco's stump grinder line, the CL-410 was found to be a suitable fit for the wood chippers.

For these relatively compact machines, the CANLink modules open up space within the chassis to do more functions. The module replaces the bulky switches, wires, relays, and fuses that would make up a standard electrical system. Driven by software, the CL-410, which is about the size of a paperback book, has the versatility to handle all the functions performed by standard components.

Along with cutting down on the cost of a huge parts inventory for individual machines, the CL-410 can be set up to monitor and control operations for seven machines with just one board. Yet, the module has the versatility to handle not only current functions but also other features that can be devised by Rayco engineers.

According to Bruce Chapman, manager of product engineering for Rayco, using the one module, "resulted in up-front savings and for everyday production we can purchase and stock one module to program as necessary."

"Inventory control loves this arrangement as the stock becomes flexible and can be converted as needed for any production schedule shift," he continues.

Added Abilities

The module give Rayco technicians the ability to program machine functions on the production floor from a laptop, using a set of algorithms developed by HED for each machine. These algorithms take into account the characteristics of each chipper model--engine size, feed rates, tooth count, blade size, rpm, and other factors--so that the product can be tuned before it leaves the factory.

HED provided Rayco with the Visual Basic/Windows package so technicians can quickly select parameters for the machine in which the controller will be installed. Chapman says that diagnostic LEDs on the module let the production personnel easily and reliably verify functions of switches, actuators, and wiring on the machine.

The same capability to program the modules within the Rayco manufacturing facility enables service personnel to diagnose any problems in the field using a laptop. This software based system also enables Rayco to develop new features than can be added to existing equipment in the field by just supplying the software patch.

The module has the base software code and Rayco technicians can do the rest in just a few minutes. Rather than doing complicated C programming or ladder logic, the user simply points and clicks to the type of machine they want.

One of the benefits of CAN technology is the ability to do datalogging and load control, as well as safety interlocks and system fault code shutdowns. The load control program can optimize performance of the engine by counting the rpm of the teeth on the feed wheel as the machine feed rate slows down. On an electronically controlled engine with an electronically controlled throttle, the module will control the engine based on the feed. If the operator leaves the feed in neutral for a determined amount of time the module will throttle the engine down to save fuel.

Interlocks programmed into machine operation protect both the machine and the people around it. With a wood chipper, the more an operator can anticipate its operation the better for safety in a variety of ways. For example, the sequence dictates that the feed does not start up until the engine does to prevent unintended movements. That is important when crews use the chippers because someone can go on break in the middle of an infeed and when everyone gets back to work another worker might start up the chipper. If this chipper was not set up with the interlock the risk exists of the machine starts up and shrubbery suddenly starts feeding in. The feed has to be turned on separately when work resumes.

For future development, Rayco is planning to use the datalogging function to record machine parameters for their own service diagnostics and to provide owners with data on how their employees are running their machines. This type of information will be useful to rental yards in tracking how their customers are using, or abusing, equipment. GPS and wireless capabilities also give owners the ability to track and update their equipment.


More information on HED Inc., 1715A Innovation Way, Hartford, WI 53029, is available at or by calling 800-398-2224.


Microelectronics have been around for nearly a half-century. What was the early integration of control ciruits like? It all started in the 1950s when an engineer named Jack Kilby, working at Texas Instruments, dreamed up the idea of an "integrated circuit."

By the end of the decade, Kilby had developed several examples of these circuits. He connected components by hand-soldered wires and isolated them by using diodes as resistors.

Meanwhile, in 1958, Jean Hoerni of Fairchild Semiconductor invented a technique for diffusing silicon to build planar transistors. But it was Robert Noyce, a co-founder of Fairchild that is credited with the first true integrated circuit. He used a planar transistor, back-to-back pn junctions for isolation, diode-isolated silicon resistors, and Si[O.sub.2] insulation with evaporated metal wiring on top.

In 1961 Texas Instruments and Fairchild introduced the first logic IC and by the mid-1960s densities and yields were improved. In 1967, Fairchild marketed the first semi-customed chip.

Microelectronics really took off in 1971 when Intel debut the first microprocessor, designed by Ted Heft. It never captured much interest in the market and was soon eclipsed by more capable units.

Starting in 1972, a microprocessor that was able to control a CPU was finally introduced. Since then, there has been exponential growth in microelectronics and today, microelectronics play a big part in controlling a vat array of applications.