D

DEAD-HEADING
Trucker poetry for driving an empty truck either on the outbound or inbound leg of   ajourney. A costly situation to be avoided!
It's a much more upbeat term for gardeners, since it means removal of faded blooms in order to encourage setting of more flowers!

DECIBEL
The standard unit for expressing relative power levels. Decibels indicate the ratio of power output to power input. 1 dB = 10 log10

DEEP CYCLE BATTERY
Two basic types of battery are used in automotive and marine applications: the Starting Battery, and the Deep Cycle.

The Deep Cycle has long been used in marine and RV applications, and is increasingly being installed in heavy trucks. Since federal and state regulations on truck length have been relaxed, there has been a trend away from COE rigs, and the sleeper cab has almost become a condo. With this change, there is an increased need to plug in appliances such as microwaves, refrigerators,TV/VCRs and computers.

The starting battery is intolerant of a large draw-down in power, but deep-cycle batteries are made to be drawn down and recharged repeatedly, and are therefore the right battery to use to power appliances. Normally an inverter is also used to convert the DC to AC.

Because both batteries need to be recharged from the same system, you will need to install a Battery Isolator.
We manufacture nine different isolators, so that you can select the right one for your application.

DEPENDENT/INDEPENDENT
Amongst other things, a designation of switch lighting.
For example, you can wire our Lighted Toggle Switches (54111) or Weather-resistant Lighted Toggle Switches (54000 series) as independent or independent.M-54111

Dependent: when you actuate the switch, the light in the switch handle comes on.
This is a visual feedback situation that reassures or reminds you that the switch is On.

Independent: the light in the switch handle is on all the time.
This is useful if you need to find the switch in a darkened location, or you need to draw attention to a specific switch.

The 54000 series also includes matching non-illuminated switches in a broad selection of functions.

Another advantage of these illuminated switches is the color of the light, whichgives a strong visual assurance of the position that the switch is in...

54111 for example Shows Red in the Up/On position, White in Mid/Off and white in the Down/On.

DIRECT CURRENT (DC)
Electrical current which flows in one direction only. All battery-driven circuits are DC.
Cole Hersee manufactures switches and components for DC applications.

DOUBLE POLE DOUBLE THROW
see Switching

DMM (DIGITAL MULTIMETER)
An instrument used to measure voltage, current and resistance. It is rapidly replacing the traditional galvanometer multimeter, which is fragile.

DISPLACEMENT (Piston Displacement)
Sum of the volumes swept by an engine's pistons as they travel up and down in their cylinders. Based upon bore (diameter of cylinder) and stroke (distance traveled by piston). Expressed in liters or cubic inches.

DRIVELINE
All the components which together transmit power from the transmission to the drive axle(s). Includes the driveshaft (propeller shaft) with a universal joint at each end.

DRIVETRAIN (Powertrain)
All the components, excluding engine, which transmit the engine's power to the rear wheels: clutch, transmission, driveline and drive axle(s).

DRL (Daytime Running Lights)
System that automatically turns on a vehicle's low beam headlights when the parking brake is released and the ignition is on. Cole Hersee part number 48600. More info: D-559

DUAL BATTERY SYSTEM
Two batteries mounted on a vehicle. Emergency vehicles and utility vehicles often have dual battery systems because of added power demand. Such systems necessitate the use of a Battery Selector Switch. More info: CF-103

DYNAMIC BRAKE (or non-dynamic)
This refers to the method by which the winshield wipers are brought to a standstill in the 'home' position. To replace a wiper switch, you will need to know which system is in place.

Explanation Check FAQs under "Wipers"