Glossary
Alphabetical Listing
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
Allison Automatic Transmission
The Allison Series 6-speed automatic transmission was designed to maximize horsepower and torque. It is electronically controlled and has six forward gears and one reverse gear. Fifth and sixth gears provide an overdrive gear ratio. The transmission is also equipped with a Tow/Haul Mode and Torque Converter Clutch that increases fuel economy.
C
Curb Weight
Curb Weight is the vehicle weight without the driver, passengers or cargo. This weight includes all the fluid levels topped up including a full tank of fuel and other items of standard equipment.
D
Dry Weight
Dry Weight is the weight of the empty trailer as manufactured. This weight, usually shown on the trailering identification plate, is not usually used as a measure for the selection of a tow vehicle.
Dynamometer
A Dynamometer is a machine used to measure power output. An engine dynamometer measures output at the crankshaft.
G
Gross Axle Weight Rating (GAWR)
The Gross Axle Weight Rating (GAWR) is the maximum allowable weight that can be carried on a vehicle's axle or individual suspension components, either front or rear. It includes the weight of the vehicle, plus cargo and equipment supported by the axle and includes Tongue Weight or Kingpin Weight when trailering. These ratings are shown on the vehicle's Certification Label, usually located in the driver's door frame, and should not be exceeded, nor should the total load exceed the GVWR.
Gross Vehicle Weight (GVW)
The Gross Vehicle Weight (GVW) is the weight of the vehicle, consisting of the standard truck weight, add-on weights for options and equipment, the weight of occupants and whatever cargo is being carried.
Gross Vehicle Weight Rating (GVWR)
A vehicle's GVWR is the maximum weight a vehicle should reach in use, including the vehicle itself, passengers and cargo, but not including a trailer. A vehicle's GVWR is established by its manufacturer and should not be exceeded for reasons of safety.
H
Horsepower
Horsepower is the measure of the amount of work that can be done in a certain amount of time. One horsepower is equal to 33,000 ft.-lb. of work per minute. The horsepower of an engine depends on the torque and speed of an engine and can be represented as Torque x RPM/5252 = Horsepower.
K
Kingpin
The kingpin is the part of the trailer that attaches to the fifth-wheel hitch. As part of the upper fifth-wheel coupler, the kingpin engages with the jaws of the fifth-wheel and holds the trailer firmly in place while letting the trailer turn freely.
L
Locking Rear Axle
A locking-type differential is available on most GMC and Chevrolet. It permits normal differential action, which prevents tire scuffing when turning. If the differential senses an excessive difference in speed between the rear driving wheels, it forces power to the wheel with the best traction. This advantage is most evident on slippery surfaces where traction is at a premium, such as on boat ramps or ice- and snow-covered roads.
M
Maximum Trailer Weight
The Maximum Trailer Weight is the most weight that a given vehicle can safely and reliably haul without exceeding any of the manufacturer's ratings.
Maximum Trailer Weight Rating
The most weight that a given vehicle can safely and reliably haul, as determined by the manufacturer, is known as the Maximum Trailer Weight Rating. This rating usually requires optional equipment such as a specific rear axle ratio, suspension components, engines and/or transmission coolers and type of hitch.
P
Payload Capacity
The maximum amount of additional load you can put on an equipped vehicle without exceeding any of the manufacturer's ratings is the Payload Capacity.
Payload Weight
The Payload Weight is the total weight that a vehicle will carry. This includes the weight of the occupants, cargo, options and other equipment.
Pickup Truck Buyer's Guide – WORKBOOK
Use the Pickup Truck Buyer's Guide Workbook while you go through the information on this Web site. Answer the questions you can and take the printed Full Workbook to your local Chevrolet or GMC Dealer. Your Sales Consultant will fill out the rest in order to help you pick the proper pickup.
R
Rear Gross Axle Weight
To calculate the Rear Gross Axle Weight you must add the cargo with half of the people load (the half being carried by the rear axle), the Rear Curb Weight of the truck and the Tongue Weight, if applicable.
S
Shipping Weight
The Shipping Weight is the weight of the vehicle as manufactured with optional equipment, but without an allowance for fuel.
T
Tongue Weight
The weight of the trailer tongue that is carried on the hitch ball is its Tongue Weight. This is a critical measurement as it has an impact on vehicle handling. Too much Tongue Weight causes overloading of the rear axle, causing the front suspension to lift and therefore reduce steering response. Too little Tongue Weight can reduce rear-wheel traction and cause excessive swaying or jack-knifing. Depending on the type of hitch being used, Tongue Weight is generally 10-15% of the Loaded Trailer Weight. Some adjustments to the Tongue Weight can be made by moving the cargo in the trailer.
Torque
Engine Torque, measured in pounds-feet (lb.-ft.) or Newton-metres (Nm), is the amount of twisting effort exerted at the engine's crankshaft. One pound-foot is the twisting force exerted by gravity on a one-pound weight suspended from a crankshaft by a horizontal rod one foot in length.
Torque Curve
Torque Curve is the graphical representation of the amount of torque available at various engine speeds.
TOW/haul mode
Most GMC trucks equipped with an automatic transmission feature a Tow/Haul mode, which helps minimize wear and tear on the transmission by reducing the frequency of transmission shifting when pulling a heavy trailer. It also improves performance and control of your vehicle's speed, for smoother operation.
Pressing the Tow/Haul mode selector switch located on the end of the gearshift lever produces a more aggressive shift pattern, which lengthens the shift intervals and produces firmer upshifts.
W
Weight-Distributing Hitch
A Weight Distributing Hitch is used for heavy trailering. This hitch, with its equalizing bars and snap-up brackets, applies leverage between the tow vehicle and the trailer to help distribute your trailer's Tongue Weight evenly to your vehicle and trailer instead of "carrying" the load mostly on the rear of the vehicle. The brackets and spring bars raise the hitch point parallel to the ground, equalizing the load onto all axles. This results in a more level ride, reduced weight on the rear suspension and provides improved steering and braking control.
Weight Distribution Factor
The Weight Distribution Factor refers to extra weight carried by the tow vehicle. Because of the “teeter-totter effect”, approximately 40% of the tongue load will come off of the front axle and be carried on the rear axle.
