4-Star Trailers 'Quiet Ride' Technology

Posted by Eileen Gorman on 01/11/2014

4-Star Trailers, Inc. is the industry leader in horse trailer design.  Trailers with the 'Quiet Ride' technology (Patents Pending) are the latest example of innovation in a long line of industry firsts that have been introduced by 4-Star Trailers.

The idea for the ‘Quiet Ride’ trailer originated some time after the Olympic Games were held in Atlanta, Georgia in 1996. The United States Olympic equestrian team enlisted the aid of 4 veterinarians to monitor the health of the team’s horses; most of which were transported from various locations around the U.S. They published an article in a leading equestrian magazine documenting their experience. The magazine in which the article appeared caught the attention of one of 4-Star’s marketing representatives who shared it with the engineering department; planting the seed for that which was to come. The magazine has long since been lost. The following is a paraphrase of that article.

In the days leading up to the opening ceremonies, the horses began arriving in Atlanta via various modes of transport, including airplanes, vans, trailers and trains. The vets examined the animals as they arrived and immediately noticed a great amount of variance in the condition of the animals. Many horses required 2 to 3 days of recovery time before being able to compete. Some required little to no recovery time. The veterinarians wondered about the next Olympics to be held in Sydney, Australia. If horses traveling a few hundred miles were not able to compete for days, how would they fare when traveling half way around the world? They needed to know why some horses which traveled over 2 thousand miles were in better physical condition than some others which had only traveled a few hundred miles.

They began researching the effects of transport on the health of horses and   found correlations between conditions during transport and animal stress levels and recovery time. They came up with a list of environmental factors associated with equine transportation which affected a horse’s ability to compete. Excessive noise and vibration were two factors cited as large contributors to increased stress.

Their research has received corroboration from other sources including The Ministry of Agriculture, Food, and Rural Affairs in Ontario, Canada1whose web site treatise on the topic of horse trailering makes these comments:

“The duration and intensity of stress can impact the horse's capacity to grow, reproduce, train, perform and maintain health.”

“A trailer that travels quietly and smoothly will provide a more comfortable and less stressful ride for the horses.”

As a leading manufacturer of horse trailers, we are always concerned about the health and safety of the animals entrusted to our products, and as such, we could not ignore this information.

We were already continuously implementing design changes to improve our trailers both structurally and aesthetically when we became aware of the impact of noisy vibrations on animal health and the importance of reducing stressful conditions caused by them during trailering. Much of what had been done in the pursuit of safety, durability and ease of use also created a trailer that is relatively quiet compared to other trailer brands. Many of the design changes whose primary reasons did not include ‘quiet’, nonetheless proved to be effective in reducing the sound levels inside the animal compartment. Such as:

Torsion Axles
Rubber torsion axles had already proven to provide a smoother and quieter ride than leaf spring suspensions and had become standard equipment on all 4-Star trailers by the early nineties. When air ride suspensions were developed for trailers with G.V.W.R.’s below 26,000lbs, we were one of the first manufacturers to offer this type of suspension to our customers. Air ride suspensions are superior in absorbing vibrations and road noise due to the air bags acting as insulators to isolate the trailer’s body from the noise and vibration generated by the tires. Air ride is an optional feature available to those customers who want the very best ride available for their horses.

W.E.R.M. Floor
In 2002 we added a new option called W.E.R.M., which stands for ‘We Eliminate Rubber Mats’. W.E.R.M. is a 2-part urethane, mixed with rubber pellets, and troweled onto a primed aluminum trailer floor forming a permanent, cushioned floor covering. While our primary reason for offering W.E.R.M. was to provide safer footing for horses and make the chore of maintaining the floor much easier for the owner, we soon realized a couple of beneficial by-products associated with its use. For one, it turns out to be a pretty good sound dampener; and two, it forms a seal protecting the aluminum floor from liquids which would ordinarily accumulate beneath removable floor mats. Moisture trapped under rubber floor mats for extended periods can create conditions conducive to the development of corrosion in the aluminum alloy floor.

Our use of Ultra High Molecular Weight polyethylene plastic or UHMW2 as wear pads, bushings, and bumpers in areas where metal-to-metal contact was often the cause of premature wear on components also had the side benefit of reducing noise levels inside the trailer.

Three years ago we received a call from a 4-Star dealer. He and a customer were out on his sales lot when they heard something coming up the road. It was a new trailer being delivered. He commented that it could be heard “A mile away”. Which turned out to be less of an exaggeration than we had at first thought.

The trailer being delivered was a model we call a 2 plus one. It is basically a scaled down version of the much larger head to head trailer popular with commercial haulers. This trailer has two straight load stalls separated from a box stall by a full width gate. The stall divider is attached via drop-in pins to removable posts at the front and rear. The removable posts are pegged into the floor and secured at the top with a spring loaded pin which can be retracted to remove the post. The design of the divider allows it to be removed, transforming the trailer into one with two large box stalls. The gate is hung on four sets of hinges made up of 3/8” stainless steel hinge pins and extruded aluminum hinge butts with washers between the gate hinges and gate post hinges. Each stall requires a butt bar and breast bar which also rely on drop-in pins and large aluminum hinge butts to secure them. 

The methods described for pinning dividers, breast/butt bars, gates, etc. are similar in all makes and models of horse trailers built in the last 3 decades. There is a lot of metal-to-metal contact in these components which generate noise as they bang against each other during transit.

4-Star Trailers initiated a concerted effort to investigate new materials and develop new components that reduce or eliminate metal-to-metal contact in the interior of all our trailers. After three years of research and testing, we built our first trailer incorporating all of the things we learned. The result is the ‘Quiet Ride’ Trailer and it surpassed our expectations.

So impressed were we after road testing3 the new trailer and doing direct comparisons with previous designs that we believe that the improvement will revolutionize horse trailer design in much the same way as our introduction of the Concept II Slat4 did.


1.    http://www.omafra.gov.on.ca/english/livestock/horses/facts/info_trailering.htm

2.    From Wikipedia: Ultra-high-molecular-weight polyethylene (UHMWPE or sometimes shortened to UHMW), also known as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE), is a subset of the thermoplastic polyethylene. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. It is highly resistant to corrosive chemicals with exception of oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating; and is highly resistant to abrasion, in some forms being 15 times more resistant to abrasion than carbon steel. Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to that of polytetrafluoroethylene (PTFE, Teflon), but UHMWPE has better abrasion resistance than PTFE. It is odorless, tasteless, and nontoxic.

3. See the road test at:  Before Quiet Ride http://www.youtube.com/watch?v=pKy08vnSIDw&feature=channel&list=UL and after Quiet Ride: http://www.youtube.com/watch?v=ie0Rwz6FgY8&feature=channel&list=UL Demonstration video: http://www.youtube.com/watch?v=ZmLNIF_81Ms&feature=channel&list=UL

4. The Concept II Slat is our patented design which reduces heat tracks and weld distortion in the side slats of trailers using them.