Why Cow-Catchers Are Helpful In A Small-Vehicle/Large-Vehicle Collision

October 27, 2009

Remember those things called cow-catchers on the front of steam locomotives? Of course, you are probably too young to have seen one in person, but cowboy movies show them. Oh, you havent had a cowboy movie lately? If you do see a choo-choo train, note that they look like they have pointed snow plows low on the front of the train. Diesel locomotives have streamlined ones that you barely notice.

There was a time when free ranging cattle roamed on highways and railroads. The cow-catcher pushed cows to the side of the tracks preventing the animal from going under the wheels. That didn't do the cow much good, but it prevented the locomotive from being derailed or even overturned.

Unfortunately, not many 18-wheeler trucks or four wheel drive vehicles have a cow catcher at the front. They do not need them for pushing animals aside. But, it is good when a big truck or tall SUV actually does have a strong bumper placed low enough to engage the bumper of ordinary cars. That is the modern cow-catcher. In a collision, the bigger vehicle will be able to push the other vehicle backwards or to one side. That push may be a hard impact for those inside the smaller vehicle but it is better than squashing the occupants into hamburger.

Driving around today, I saw a COE (Cab over Engine) truck that reminded me. Years ago the laws allowed the COE truck to have a set-ahead front axle. That meant the front axle was placed so close to the bumper that the tires were barely behind the front bumper. That made for the shortest wheelbase, which enhanced the maneuverability of the truck. In-town trucks benefited  from that.

The people around them did not benefit. It was common to see that the truck operator removed (clipped off) the ends of the bumper. The driver knew that if the truck tapped anything at the front corner the bumper would bend backwards and jam the tire and lock the steering. Clipped bumpers exposed the tires to direct contact from the front and sides. With good traction between hot tire-rubber and a dry surface of a car, COE trucks would climb up onto the hood or trunk of a car that they hit. Sometimes the truck went up far enough to crush the passenger compartment. Lots of them did that.

When I take a long boring trip on the Interstate highway, I amuse myself by looking at the vehicles coming in the other lanes. I count the number of Cab-Over-Engine (COE) tractor-trailers. I see less than 10 during a two hour trip. Why so few? The advantages the COE trucks had are gone. Years ago the short-tractor truck was very popular because of the limitations on the length and width of the trucks. Until 1984, the maximum length allowed on any highway in any state was 50 feet for the tractor and trailer.  That explained the popularity of the COE tractor for highway use. The COE was also popular for short-wheelbase maneuverability downtown.

Those semi-truck rules were relaxed. A long-nose tractor could be 17 feet long; the semi could be 53 feet and the combo 80 feet long. Now long-nose long-wheelbase tractors are the preferred thing. A benefit of the longer wheelbase is a less-tiring ride and it allows for a full size sleeper compartment. Most long-nose tractors have set-back front axles, and full bumpers so there is no need to clip the ends off the front bumpers.

Big tractor-trailer trucks sometimes have impressive looking front bumpers. However, if the bumper is just a pretty face to push aside the wind, not strong like a cow-catcher, those awful things I mentioned can still happen in a collision. This is just as true for jacked up pickup trucks. If the front bumper does not match up with the bumper of an automobile it will smash the sheet metal of the trunk or the hood of the car. Once the truck crumples that sheet metal, the hot rubber tires get a strong grip and ride up on the smaller vehicle. In my work, I have seen a tall pickup or Jeep-type vehicle walk up on the hood and put its bumper right in the face of the driver of the car.  Not nice at all. I have also seen the walk-up truck squash the trunk and the fuel tank under the trunk causing the tank to pop like a grape. Nasty stuff.

There is not much you 4-wheelers can do about this problem. Hope that the auto and truck industry gets serious about cow catcher bumpers, and that the big wheel boys restrain themselves. The government made laws requiring car bumpers to be within a certain distance from the ground. Once the vehicle is sold, the owner can do just about anything he wishes, including jacking the SUV up with big wheels and tires.

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