Pulling Trailers Safely
Whenever an employee jumps into a company pickup to hook onto a trailer, the employee might use his basic understanding of the truck’s power to determine if the truck will pull the trailer. The trouble is that the truck might pull the trailer, but the hitch might not do the job safely.
When there is a hitch attached to the truck, the assumption might be that the hitch would be heavy duty enough to allow pulling the maximum weight for the power and series of truck. A company needs to be sure that every truck’s hitch components—receiver, insert and ball—are consistent for pulling a known weight, and employees need to know the pull weight to keep from attaching too heavy of a load to the truck.
The other big concern has to be how heavy duty is the trailer. Has it been built so that it can handle a reasonable load? The weight of the trailer takes away from the amount of goods that can be loaded onto it. Low strength components used to manufacture a trailer limits its hauling capacity quite drastically.
“When you order a new truck and you know you want an F350, or any other brand, you also know you want it to pull x amount, you don’t just buy any F350,” said Fred Whitford, Ph.D., Purdue University pesticide programs, during his presentation at the National Agronomic Environmental Health and Safety School last summer.
Whitford and others authored the large-format 84-page booklet, “Keep the Trailer Connected to the Truck,” which can be downloaded here. It is also available from the university in high-gloss color bound editions.
Whitford went on to explain that the first requirement is to make sure and order a truck with the hitch receiver factory installed that closely matches the maximum pulling specifications for your needs—paying more for the heavier duty hitch receiver can be a fairly expensive upgrade. A standard hitch receiver will usually not match the maximum pulling power of the truck.
Not ordering with a heavier duty receiver is the big mistake that cannot be cleared up after leaving the factory. The receiver is the number one consideration. And underneath the truck on the hitch receiver is a tag that lists the carry weight, which is the maximum pull weight.
INSERT AND BALL RATING
Inserts that go into the receiver also have ratings. Whitford said there are various insert ratings, just like the receiver maximums.
He then quizzed the audience of agricultural retailer safety coordinators about the maximum pull potential. He asked if a truck can pull 9,000 pounds, the receiver hitch is tagged at a rating of 7,500 pounds and the insert is rated at 10,000 pounds, how much weight can safely be pulled? The answer is 7,500 pounds or the lowest rated segment of the pulling system.
The pin that holds the insert in the receiver should specifically fit the drilled hole, but Whitford explained that the pins are not load rated. “In talking to people who work in the industry, they say there isn’t that much pressure on the pin,” he said.
The ball that attaches to the insert does have its own rating. Example of a rating range for a two-inch ball maximum pull rating might be 3,500 pounds to 10,000 pounds. Whitford noted he found a two and 5/16th inch ball rated for 30,000 pounds.
A cheap ball can be the undoing of a hitch system’s safety. Whitford provided another example. He suggested a truck can pull 12,400 pounds, the receiver is tagged for 7,500 ponds, the insert is rated for 5,000 pounds and the ball is rated for 3,500 pounds; therefore, that really powerful truck can legally only pull 3,500 pounds.
Whitford used another example of a trailer weighing 4,300 pounds. The hitch ball is rated at 6,000 pounds and is the lowest rated of the three hitch components (receiver, insert and ball); therefore, legally the trailer can only be loaded with 1,700 pounds to not surpass the 6,000 pound maximum of the ball. The weight of the trailer has to be considered part of the total amount being pulled—4,300 pounds plus 1,700 pounds equals the 6,000 pounds of the ball rating.
MORE SAFETY CONSIDERATIONS
“The safety chain is your emergency protection if something comes unhooked,” Whitford noted.
A hard-working truck needs a hitch of receiver, insert and ball components of equal ratings to pull heavy loads. Chains have to be easily attached but securely attached, he explained. Employees can sometimes look to take the quick way out when in a hurry, but the chains have to be crossed, not twisted.
“If the trailer comes off, it is going to pull both chains as the truck and trailer separate, when it does that it forms an X, and the hope is that the trailer tongue will fall and rest on the chains,” Whitford said.
The chains should not be twisted because the chains are not at maximum strength when twisted. “When they test the chains and give them grades for strength, it is done in a straight pull. When you twist them, I’m told they break differently than as tested.”
The proper strength chain for the trailer and a chain that has never been broken or has been properly repaired to maintain its original strength is mandatory. Many repair options greatly compromise the strength of the chain, Whitford showed through example.
TRAILER HAULING CAPACITY
Each trailer has a gross vehicle weight rating assigned to it by the manufacturer based on the materials used to build the trailer. The gross vehicle weight rating is the total of the weight of the trailer plus the weight of what can be put on the trailer. Whitford said that some manufacturers aren’t quick to volunteer the gross vehicle weight rating.
A cheap trailer can be big and really look good, but it might be rated for hauling a very light load as Whitford pointed out in an example. “We think that a trailer can carry a lot because it is a big trailer, but as it turns out this is a worthless trailer. It looks good; it looks nice, and it has two axles. But it is a cheap trailer. It is not meant to carry heavy loads.”
The example Whitford used was of a 7,000 pound gross weight trailer weighing 2,400 pounds. That means the payload is only 4,600 pounds, even though it is a big tandem axle unit. A load of 4,600 pounds is about the equivalent of two pallets of products hauled by an ag retailer—not six pallets that the trailer’s size might allow on its bed.
Additionally, the trailer load needs to be balanced so that there is some weight on the tongue, but not too much. The load should neither tip the trailer onto the tongue too much nor off of the tongue with all the weight at the back of the trailer. The back end of the truck should not be pushed down too much.
“What helps keep a trailer hooked is some weight on the tongue; we want enough weight to help keep the trailer’s tongue pushing down on the ball,” Whitford noted.
Hundreds of trailer accidents happen every year, and a trailer that becomes unhitched in one way or another is a dangerous weapon with the potential to kill and maim. No one wants faulty equipment to be the reason for a fatality, he said.
Even in a minor accident, the investigation involving a trailer will come down to looking at the hitch system and the load capacity.
Being insured when an accident occurs is of major importance, too, and Whitford told the audience to check their vehicle insurance policies to see if the policy covers what happens when a trailer comes unhitched.
“Many insurance policies require you to list that trailer in the vehicle policy because once the trailer comes off and it isn’t listed, it isn’t part of the vehicle,” he said.
“I view transportation as the number one risk that we face,” Whitford said. “In my opinion, from all my years, it is not pesticide poisoning; it is not releases of dangerous chemicals or any of those other things we try real hard to avoid. It is the real simple things we do when on the highway that are the most risk.”
This article is brought to you in cooperation with the National Agronomic Environmental Health and Safety School (NAEHSS).