TOWING_SPECS2.doc

Medium-Duty Towing Dynamometer

A towing dynamometer (see Figure 1) is a trailer-type vehicle used in a towing configuration to apply a measured load to a vehicle to simulate forces generated during travel over road profiles involving grades, hills and mountains. Towing dynamometers are generally designed for use in a controlled environment on a level test track to assess vehicle performance characteristics such as power, speed, and cooling ability.

Figure 1. Towing dynamometer (white) coupled with test item.

New Medium-Duty Towing Dynamometer Specifications:

· Eddy current power absorption towing dynamometer with self-contained control system.

· Minimum-rated drawbar ceiling of 5620 lbf (25 kN); 5200 lbf @ 17 mph, 3900 lbf @ 25 mph, 2150 lbf @ 45 mph, and 1500 lbf @ 60 mph continuous rating; 3250 lbf @ 35 mph and 3000 lbf @ 45 mph short-term (3-minute) rating.

· Maximum test-capable speed of at least 70 mph.

· Single-speed transfer case.

· Industrial heavy-duty diesel generator for on-board power.

· Hydraulic surge brakes.

· Parking brake.

· Air-ride suspension with auto-leveling capability.

· Tie-down rings on chassis/frame for transport use, appropriately sized to secure the trailer’s maximum ballasted weight.

· Weather and water resistant body protecting the essential trailer control systems and contents from rain, accumulations of ice and snow, and accumulations of road dirt, when being towed. The body enclosure need not be equipped with watertight seals provided the sensitive equipment it contains does not get wet and the water readily drains from the enclosure. The frame and body need to be corrosion resistant.

· Adjustable lunette tow ring, 3-inch ID loop, appropriately rated for the trailer’s maximum ballasted weight (eg. Buyers PN B-16137).

· Adjustable hitch height: The lunette tow ring needs to be adjustable in height to accommodate attachment to a variety of vehicle pintles varying from 24 to 42 inches above the ground (threshold) or 20 to 45 inches above the ground (objective), while maintaining adequate ground clearance at the hitching location. Once attached to the towing vehicle within the specified height range, with the landing leg retracted, the towing dynamometer’s tongue assembly (or the load cell location) needs to be level within +/- 2 degrees. If such an option is not possible, the tow dynamometer tongue needs to accommodate a removable lunette tow ring (of the size specified above) so ATC can make custom mounts as needed. In either case, the drawbar shaft, bearings, and surrounding support structure shall be sized to handle the applied moment encountered at full-rated drawbar load and maximum specified hitching height.

· Manually adjustable and retractable landing leg (tongue jack) with a heavy duty wheel, rated to support the anticipated tongue load of the fully ballasted trailer, and enough travel to accommodate the full range of hitch heights listed above plus 2 inches.

· Trailer lights: The brake, service, and running lights should be able to be connected to the towing vehicle via an included NATO intervehicular electric cable extending a minimum of 2 feet past the front of the trailer lunette with 12-pin connections meeting NATO STANAG 4007 pinout standards and having a male MS 75020-1 connector on the towing vehicle end of the cable. An electrical converter module may be installed on the trailer to convert the 24-volt truck signals to the trailer 12-volt signals as needed (eg. SEC America PN UTC 2412-7H).

· A means of overload protection, either physical or electrical to prevent serious damage to trailer and towing vehicle if the drawbar is accidentally overloaded or commanded to be overloaded via the dynamometer controller.

· Controller unit with touch screen wireless control capability and integrated graphic driver display.

· Wireless connection communication capability between dynamometer and controller unit.

· Wired (Cat 5 or Cat 5e) connection communication capability between dynamometer and controller unit (minimum 30 feet of cable).

· CAN bus output from controller with standard DB-9 connector and database configuration file (.DBC) included.

· Absorber temperature monitoring via the dynamometer controller unit.

· Output linear, conditioned analog 0-10 volt range signals proportional to the calibrated load cell-measured load and road speed via separate BNC connectors (or similar) on main dynamometer unit or controller in an easily accessible location.

· Removable load cell for off-site external calibration of load cell disconnected from dynamometer.

· Removable load cell for on-site external calibration with enough cable to keep load cell electronically connected to dynamometer and corresponding instrumentation.

· Documentation: Operator’s & Maintenance manuals containing appropriate assembly drawings, figures or schematics of the data acquisition and controller system, wiring schematics of the system, details of the control software operation, troubleshooting and diagnostic procedures, and calibration procedures.

· 2-year warranty: parts and labor, excluding normal wear items (e.g. tires, batteries).

· 2-year service plan: free technical phone/email support and 48-hour rush spare parts service.

Note: Any mention of branded products in the above specification should not be construed as an endorsement, but used only as an example of equipment that’s readily available in the marketplace.