Landscape & Irrigation

November/December 2017

Landscape and Irrigation is read by decision makers throughout the landscape and irrigation markets — including contractors, landscape architects, professional grounds managers, and irrigation and water mgmt companies and reaches the entire spetrum.

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18 November/December 2017 Landscape and Irrigation www.landscapeirrigation.com FLEET MANAGEMENT BY BOB RAYBUCK T railer towing involves three primary elements: the work truck used to tow; the trailer and payload being towed; and tow ing system components (e.g ., hitch system and safety chains). Each has limiting f a c t o r s t h a t d i r e c t l y a f f e c t m a x i m u m towing capability. Truck salespeople, fleet managers and end users face challenges in determining size and capacity of the trailer that can be towed based on the work truck specified or purchased. First, let's review the tow ve h i c l e's r a t i n g . Tr u c k m a n u f a c t u re r s publish maximum trailer tow rating and gross combined weight rating (GCWR) in the trailer towing guide or as part of the vehicle specification guide. Additionally, t h e t r a i l e r t o w i n g g u i d e m a y i n c l u d e maximum t r ailer tow r ating s based on conventional towing (which uses a coupling device attached to the rear of the towing ve h i c l e ) o r f i f t h w h e e l tow i n g ( w h i c h utilizes a coupling device attached to the top of the chassis near the rear axle and is sometimes referred to as a gooseneck). Alternatively, medium- and heavy-duty truck dealers provide information based on the OEM order guide or through application engineering departments. The ch a s s i s m a nu f a c t u rer de ter m i n e s G C W R u s i n g a v a r i e t y of factors, including specific drivetrain components of the engine, transmission, number of drive axles, axle ratios and braking capability. Each OEM tests chassis towing and stopping capability before determining vehicle GCWR. Chassis manufacturers also provide maximum trailer weights for conventional and fifth wheel/gooseneck towing. Normally, these maximum trailer weights are for complete vehicles such as pickups and vans, and do not include work trucks built from incomplete chassis. Truck GCWR helps determine maximum trailer towing capacity. Both the weight of the towing vehicle and the trailer (towed vehicle) are included in the GCWR total. Essentially, vehicle trailer towing capacity is determined by remaining GCWR after taking into consideration chassis, truck body, equipment, passenger, fuel and payload weight. The amount of payload carried on the work truck can raise or lower maximum trailer towing capacity. For example, if your work truck has a 26,000-pound GCWR and 19,000-pound gross vehicle weight rating (GVWR) and is completely loaded to the GVWR, maximum trailer weight would be 7,000 pounds — even if the truck manufacturer stated the maximum trailer weight was 11,000 pounds. The second element of trailer towing is trailer GVWR — the maximum allowed weight of the trailer and its payload, which can be found on the required trailer certification label. Typically, the certification label for a trailer is a metal plate welded or riveted to the forward half of the left front. Trailer GVWR will be based on the limiting factors of the axle(s), tires, frame, coupler and safety chains. The trailer manufacturer is required to take all components into consideration when determining final GVWR. The third factor in trailer towing is the trailer coupling system, which contains the components necessary to connect the towing vehicle and trailer. Conventional trailer, fifth wheel and gooseneck towing systems are rated by SAE International Standards. SAE J684 Trailer Couplings, Hitches, and Safety Chains- Automotive is for conventional type trailer towing SAE J2638 Fifth Wheel and Gooseneck Attachment Performance Up to 30,000-lb Trailer Gross Vehicle Weight is for lighter duty fifth wheel and gooseneck type trailer towing Trailer towing What you need to know for risk management PHOTO COURTESY OF RAM If your work truck has a 26,000-pound GCWR and 19,000-pound gross vehicle weight rating (GVWR) and is completely loaded to the GVWR, maximum trailer weight would be 7,000 pounds — even if the truck manufacturer stated the maximum trailer weight was 11,000 pounds.

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