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Double-J Rim

The double-J shaped safety locks on a rim, used to hold the inner and outer tire beads securely.

Double-lid Box

A crossover tool box for a pickup truck's bed that has two lids, one on the driver's side and one on the passenger side. These lids are hinged at the back of the box, so they swing open toward the cab.

Double-reduction Differential

A differential that contains extra gears to provide additional gear reduction.

DOV

Dual orifice valve.

Dowel

A pin inserted in an object or part to aid in the alignment of another object or part.

Dowel Pin

A round, solid, or hollow pin used to align two or more parts.

Down Payment

Money paid to make up the difference between the purchase price and loan amount.

Downdraft Carburetor

A carburetor having a downward airflow.

Downflow Radiator

A radiator in which the coolant flow is from the tip tank to the bottom tank.

Downforce

The downward force of air on a speeding vehicle.

Downloading

To copy data (usually an entire file) from a main source to a peripheral device.

Downshift

The automatic shift from a high gear ratio to a low gear ratio.

Downshift Valve

An auxiliary shift valve that increases throttle pressure to force a downshift under high driveline loads, also called a kickdown or detent valve.

Downstream

A direction indicating the location of a component or fault from it's source.[1] A downstream 02 is after the cat. [2] A open in the circuit may be downstream (toward the ground) or up-stream (toward the positive) from the point in the circuit y where you are testing.

Downstream Blower

A blower arranged in the duct system so as to pull air through the heater and/or air-conditioner core(s).

Downtime

1. The time a system or machine is not available for use, due to failure or routine maintenance. 2. Time lost due to lack of service orders.

Downward Spring-and-wheel Action

A term used for rebound travel.

DP

Dash pot.

DPD

Dual point distributor.

DPDIS

Dual plug distributor-less ignition system.