Glossary of Automotive Terms – Y

Letter Y – Dictionary of Automotive Terms

A letter rating for tires to indicate that they are theoretically rated for speeds up to 300 kph (186 mph), as in P220YR15.The next higher rating is Z and the one lower rating is W
YamahaClick image for books on

A Japanese motorcycle manufacturer

Yard Horse
A tractor for moving trailers short distances in a truck yard or terminal compound. Also called switching tractor, yard tractor, trailer spotter, yard dog, and linehauler. Equipment is manufactured and sold for such exclusively off-road use, but sometimes old, spare, or unroadworthy tractors are used.
Method of transport from harvest area to storage landing.
Yard Jockey
A person who operates a Yard tractor
Yard Mule
Special tractor used to move trailers around a terminal, warehouse, distribution center, etc. Also called a Yard Tractor
Yard sale
A bicycle term borrowed from skiing where a serious crash leaves all your various wares — water bottles, pump, tool bag, etc. — scattered as if on display for sale.
Trucker slang for Mile markers on the road side as in ‘There’s a smokey advertising at the 75 yardstick.’
Yard Tractor
Special tractor used to move trailers around a terminal, warehouse, distribution center, etc. Also called a Yard Mule
The rotation about a vertical axis that passes through the car’s center of gravity.
Yaw acceleration
A steady increase in the yaw angle
Yaw angle
The angle of deviation between a vehicle’s longitudinal axis and its true direction of motion, i.e., the difference between the direction a vehicle is pointing when cornering and the direction in which it is actually moving


A Y-shaped belt design used to restrain babies in a baby seat

A Y-shaped connection of the three stator windings of an alternator
Any connector in the shape of the letter Y — often referring to a hollow unit. For example, the line coming from the Windshield washer pump is connected to the bottom part of a Y and the two tubes going to the windshield nozzles are connected to the upper part of the Y. It differs from a T-connector in that the V-shape is straight across.
Yellow boot
Colloquial term for a Denver boot
Yellow flag
A solid yellow flag (called a caution flag) is used to slow down the racers in the case of a crash, debris on the course (like car parts), slick fluids on the track or the weather has become a factor with rain. During a yellow flag the pace car, with the top lights flashing, joins up with the race leader and sets a slower speed on the track. This is done to preserve the driving order on the track as cars cannot pass one another under a yellow after crossing the start/finish line. Drivers generally use this time to hit the pits for refueling, new tires, and adjustments. It is an advantageous time to make up the distance behind the car in front of you.
Yellow-Flame burner
A burner in which secondary air only is depended on for combustion of the gas. Also called Luminous burner
Yellow line
Yellow lineClick to supersize dictionary author

The line that is painted on a road to separate a driving lane from the on-coming lane.

Yellow shoe
Colloquial term for a Denver boot
  1. The resistance to a load pulling on the middle of a fastener until the fastener shows permanent deformation.
  2. Give way to other road users
Yield Point
The stress necessary to produce an elongation under load of 0.50 per cent of the specimen’s original length. Expressed as psi.
Yield strength
  1. Stress in psi at which a specimen assumes a specified limited permanent set.
  2. The amount of pressure required to cause permanent deformity.
  3. The stress at which a material exhibits a specified limiting set, commonly taken by the offset method as 0.20 per cent of the specimen’s original length. Expressed as psi.
Yield value
  1. Minimum force which must be applied to an adhesive, coating or sealer to start the molecules of the adhesive flowing over one another, ending eventually in bond failure
  2. The amount (gallonage) that a given adhesive, coating, or sealer formula will yield in actual production.

  1. A triangular metal piece used to connect the main brake cable with the Stirrup cable in a centerpull brake system. Also known as a Saddle or pick-up.
  2. A bracket or Coupling.
  3. A forked parts of a U-joint connected by the spider.
You got a copy on me?
Trucker slang for Do you hear me? as in ‘You got a copy on me there eastbounder?’


A Y-shaped down pipe connecting a two-branch exhaust manifold to a single exhaust pipe


YugoClick image for books on

A model of automobile manufactured in Yugoslavia. Includes Cabrio (1990-91), GV (1988-91), GVL (1988-89), GVS (1988), and GVX (1988)