Episode 181: Square Wheels

Air Date: April 8, 2012

A vehicle fitted with square wheels can provide a smooth ride if driven fast enough.

plausible

Adam and Jamie designed a set of square wheels to support the weight of a pickup truck, then cut the treads off a set of tires and fitted them on. They set up a test course, using a heavy-duty pickup equipped with vibration sensors, and drove a control run (using round wheels) at speeds up to 60 mph (97 km/h). When the square wheels were mounted, the ride was very rough at first but began to smooth out as the speed was increased. However, one wheel fell off after only a few seconds when its bolts snapped.

For small-scale testing of other wheel orientations, Adam and Jamie returned to the shop and built a cart to run on a treadmill. They found that if two opposite-corner wheels were turned 45 degrees out of phase with the others, the cart achieved a balance of smoothness and stability. A full-scale test at almost 20 mph (32 km/h) caused the tire treads and brake pads to come off the wheels. Despite the mechanical failures, they classified the myth as plausible, based on the sensor readouts and their own sensations.

Square wheels can give an advantage in hill-climbing when compared to round ones.

busted

Adam and Jamie set up a dirt track consisting of a straight stretch leading to a steep uphill run. They believed that the square wheels might reduce pressure on the soft dirt and/or allow the car to dig in and get better traction. However, the truck climbed the same distance up the hill with either round or square wheels, leading them to judge this myth as busted.

The following three myths are based on a scene of the film Date Night, in which a taxicab and a sports sedan are stuck together by their front bumpers. The Build Team obtained two cars similar to those used in the movie, tore off their front bumpers, and built a hitch to hold them together nose-to-nose.

Two cars, stuck together nose-to-nose, can drive in a straight line.

confirmed

With Tory in the cab and Grant and Kari in the sedan, Grant and Kari successfully pushed Tory backwards, but could not steer very well. They obtained a similar result in reverse, with the cab pushing the sedan.

Two cars, stuck together nose-to-nose, can go around a 90-degree turn.

busted

Grant and Kari began by pushing Tory, but were unable to turn. When they introduced changes to replicate the movie scene more closely (wet pavement and bald rear tires on the cab) they obtained the same result. However, one last test with Tory pushing caused the cars to overshoot the turn and veer off in the opposite direction. Grant hypothesized that this result was due to the fact that the cab had rear-wheel drive, while the sedan had all-wheel drive; the cab’s rear wheels slid out when it lost traction in the attempted turn.

Two cars, stuck together nose-to-nose, can complete a 180-degree spin.

confirmed

After receiving some tips in defensive driving, Tory pushed Grant and Kari at 50 mph (80 km/h) toward a patch of wet pavement. When they turned their steering wheels in opposite directions, the cars went through a 180-degree spin, suffering some damage to their wheels and tires. Grant explained that the film maneuver was accomplished with extensive car modifications and a stunt driver.

1 Comment

  1. peter clayton says:

Leave a Reply

(required)