Because not all trailers are built alike, component specs should be checked to ensure the trailer is actually designed to handle the rigors of heavy hauling.
Component ratings can vary widely for models even within the same capacity class. For example, the axle wall thickness on a 25,000-pound axle might be .416, .625 or .750, depending on the manufacturer. Vertical travel on hydraulic removable goosenecks can range from 16 inches to as high as 45 inches. And flooring thickness can vary substantially. Nominal thicknesses can mean various things, so find out what the actual deck thickness of the flooring is and what kind of flooring is being used.
There are a variety of braking systems available on today's trailers: air, electric, electric/hydraulic, hydraulic/surge. The type of braking system available typically depends on the size (GVWR) of the trailer.
Air brakes are used on the larger trailers, usually those over 40,000-pound GVWR. This size has large brake shoes and various size air chambers to apply the brakes, giving the vehicle the stopping power needed.
Trailers between 26,000 and 40,000 pounds GVWR might have either electric or air brakes depending on the axles available. This is usually determined by the towing vehicle the customer is planning on using.
Electric brakes are the most common from 3,000- to 26,000-pound GVWR. They can be used with a variety of towing vehicles via the use of an electric brake controller that is independent of the tow vehicle brakes.
Electric/hydraulic brakes are starting to be used more. With electric/hydraulic brakes, you'll need an electric controller in the tow vehicle, which controls an electric pump on the trailer, which in turn applies hydraulic pressure to the brake shoes.
Hydraulic surge brakes become operative when the towing vehicle decelerates, causing the trailer to apply a pushing force against the hitch. The pushing force actuates the hydraulic cylinder in the hitch, transferring high-pressure brake fluid to the trailer wheel cylinders.
Hydraulic surge brakes have been the industry's standard braking system on trailers up to 12,000-pound GVWR for many years and are desired by many rental businesses because of their ease of hook-up (no wiring, no separate actuators, no delays). With electric brakes, a brake kit or electrical hook-up is necessary.
For several years, there was a cloud of confusion as to whether hydraulic surge brakes were considered "legal." In response to a petition for rulemaking from the Surge Brake Coalition, the Federal Motor Carrier Safety Administration proposed in October 2005 to amend the Federal Motor Carrier Safety Regulations (FMCSRs) to allow the use of automatic hydraulic inertia brake systems (surge brakes) on trailers operated in interstate commerce. This type of brake is again available provided the GVWR of the tow vehicle and the GVWR of the trailer meet certain criteria.
A trailer must be serviced like any other piece of equipment, therefore maintenance features need to be considered when
Maintenance-related features include items such as rubber-ride axles, which eliminate the need to maintain spring shackle bushings on a regular basis, and sealed modular wiring systems with internal ground wires and integral circuit breaker protection, which protect the trailer as well as the tow vehicle.
Additionally, a trailer design that lends itself to quick replacement of hitch couplers, jacks and "hydraulic brake controllers" — if allowed by individual state law — makes replacing these highly abused items a simple maintenance repair issue for rental businesses.
The supplier connection
A final consideration during the selection phase is the supplier itself. A knowledgeable trailer manufacturer that can match the trailer to your equipment and understands your industry is a must.
Purchasing from a manufacturer that provides experience along with knowledge of the industry, as well as consistency of parts and components goes a long way toward your benefit. More importantly, if you need an insurance liability policy, they'll be in the wings.