NAFTA Nations Seeking Agreement On Truck Size, Weight Regulations

May 1, 1997
WHAT will future electrical systems of trailers be like? TTMA received a preview of the possibilities when two engineers presented updates on advancements

WHAT will future electrical systems of trailers be like? TTMA received a preview of the possibilities when two engineers presented updates on advancements in truck and trailer electronics.

Jim Tipka, chief engineer for vehicle testing at Freightliner, and Tom Wissing, chief engineer for outside technology at Eaton Corporation, shared the podium at a session titled "Development of Tractor/Trailer Future Connectors."

Both men are involved in separate consortia that are working to expand the capabilities of trailers to deliver a wide range of safety and operational benefits. Participating in the projects are major trailer manufacturers, including Great Dane, Wabash National, and Utility, tractor manufacturers, and component suppliers.

Tipka began the session with a report on the results of his consortium. Participants include Freightliner Corp, Ryder Transportation Services, Vehicle Enhancement Systems, Volvo/GM, and the Department of Transportation. Outside the meeting room, TTMA members were able to view examples of the advanced equipment.

During his formal presentation, Tipka showed three communications links his consortium has used to transmit data between tractors and trailers. One is a modified ISO 3731 connector, and another is a 13-pin connector-an existing seven-pin connector with six additional pins staggered between them. The third is an infrared connection mounted on the gladhand. Data travels this link along a fiberoptics line.

"We believe it's important that these communications links be compatible with existing equipment," Tipka said. The idea is to develop a communications link that customers will accept, that only can be hooked up correctly, that is reliable, and that is not proprietary or patented. Of the three links on our truck, only the ISO 3731 follows these criteria."

The infrared connector mounted on the gladhand has proved to be a viable means of communication between tractor and trailer.

"There has been some question whether it can live in the contamination of the gladhand," Tipka said. "So we filled the connector with grease. Even with about a half inch of grease, all the signals in and out were able to pass through it."

What It Can Do

Among the capabilities of the truck and trailer:

  • Control of the refrigeration unit from the cab of the tractor.
  • Video transmission. The video camera at the rear of the trailer transmits a picture of what is behind the trailer by means of a shielded cable for RS 170 communications, passing through the 13-pin connector.
  • Satellite tracking. Signals are transmitted from the trailer to the tractor, then via a satellite communication link that can be sent back to the base of operation.
  • A collision warning device.
  • A tire-inflation system notifies the driver once pressure in a tire drops below a predefined threshold.

"The Truck Manufacturers Association and the TTMA have agreed to go forward with the ISO 3731, which is a two-connector system," Tipka said. "It provides an additional ground which will give us more power capability to the trailer. Right now, we are power-limited by the single ground lead to the trailer.

"It will also give us a hard wire for the warning light that will be required in the year 2000, plus constant power for ABS and potential diagnostics from electronic devices on the trailer and tractor."

Benefits of Multiplexing

Wissing followed with a report on TruckMux, another concerted effort between a variety of companies. The consortium is experimenting with multiplexing, the practice of sending multiple signals over the same line in order to increase the capability of the standard J560 connector.

Using the traditional J560 connector, TruckMux switches the brown and green wire to serve as J1939 communications lines. The remaining four pins provide fulltime power.

Wissing said the TruckMux project had to meet the following criteria:

  • Provide for the foreseeable needs of advanced trailer systems.
  • Be compatible with vehicles not equipped with TruckMux.
  • Use standard J560 seven-pin connector and J1067 cable.
  • Perform normal trailer functions-without intrusion.
  • Be transparent to the driver in hook-up and operation.

The TruckMux demonstration unit consists of a 53-ft Great Dane controlled-temperature van pulled by a Peterbilt 385 tractor. The tractor is equipped with Caterpillar C-12 engine and Eaton 10-speed Auto-shift transmission.

A wide range of data regarding the operating parameters of both truck and trailer can be displayed on a computer screen mounted inside the cab. Among the data that can be captured:

  • A real-time display showing the engine fuel economy.
  • A picture of the transmission shifting.
  • Torque impulses of the traction control system.
  • Vibration caused by striking a pothole.

TruckMux uses J1939 protocol standard. While ABS is helping to drive the research into new tractor-trailer connectors, TruckMux is capable of going beyond the needs for powering ABS. It can monitor a wide range of vehicle functions, including:

  • Brake health. Pressure sensors in the air tank and lines can alert the driver when pressures are low. Sensors also can be used to let the driver know the status of the parking brake and the condition of brake linings.
  • Suspension health and loading. The height and pressure of air suspensions can be used to calculate the gross vehicle weight.
  • Accident avoidance. The vehicle can be equipped with collision warning systems at the front, side, and rear.
  • Tracking and security. This includes a door-ajar warning and satellite tracking systems that pinpoint vehicle location.
  • Advance lighting that would indicate shorts and open circuits.
  • Cargo health. Refrigerated loads can be monitored for temperatures, operational settings, and trends in temperature. Alarms could notify the driver when necessary.

Four Choices

To make these advanced capabilities possible, tractor and trailer engineers have four basic options, Wissing said.

1. Add wires. This can be done either by addition of a second connector or by putting more wires in a single cable.

2. Use a power line carrier. This uses proprietary protocol.

3. Muliplexing. TruckMux switches at least two wires to utilize J1939 public protocol, sending multiple messages down a single wire.

4. Wireless. This is similar to a cellular telephone or radio transceiver for communicating between tractor and trailer.

"You are experiencing the beginning of communications between tractor and trailer," Wissing said. "Whatever you can dream, we can do. It will be up to you to make your needs known."