truck electrical accessory (fundamentals)

hydraulic electrical
pump battery
flow amperage (current)
- pump create flow - load draw amp
pressure voltage
- load - resistance to flow create pressure - load - battery (source) create vol

Mack:

  • red: straight from battery (not protected with fuse)
  • black: ground
  • white: protected
  • 2.0 metric wire size
  • wire: 36-A-2.0
    • fuse 36
    • first component in circuit
    • 2.0mm wire size
  • American Wire Gauge (AWG)
    • smallest wire: 18 gauge - 0.8mm
    • 16 gauge - 1.0mm^2 (area of cross section)
    • 14 gauge - 2.0mm^2
    • 12 gauge - 3.0mm^2
    • 10 gauge - 5.0mm^2
    • 8 gauge - 8.0mm^2
  • pull in go through the motor
  • hold in go to battery
  • relay
    • 30 power in
    • 87a (NC), 87 (NO) out to the load
    • 85, 86 (ground) pull in wiring
  • fuse
    • type 1: (gold) once stay strip, will constantly reset (head light) (no heater)
    • type 2: (silver) has resistor (heater) inside to keep bimetal from reset
    • type 3: manual reset with button
  • NTC: negative temp coefficient
    • excess current, resistance decrease
  • PTC: positive temp coefficient
    • circuit protector devices
    • excess current, resistance increase
  • electrical is drawn in non energized position
  • switches
    • SPST: single pole, single throw, ON-OFF
      • poles: sets of terminals
      • throws: positions
      • the pin in the middle is voltage in
      • the pins in top or bottom are voltage out
    • SPDT: single pole, double throws, ON-ON or ON-OFF-ON
      • control 1 circuit the same time although we have 2 separated circuits
    • DPST: double poles, single throw
      • control two separated circuit at the same time
    • DPDT: double poles double throws
  • tractor/truck: signal override brake
  • trailer: brake and signal are separated
  • acid core solder has an internal acid flux that will react with cooper wire to cause corrosion and increased resistance, use rosin core solder
  • silver the best conductor
  • power line use aluminum with steel core
  • the solenoid’s magnetic field collapses when the voltage is removed, the collapsed voltage creates an induced voltage (self-induction) causing arcing at the switch
  • clearance/marker & tail light
    • control by master lighting switch
    • clearance/marker light - armber, yellow, upper region of the truck outline
    • tail light - red - rear dimension
  • fiber optic dash illumination
    • used light source to illuminate
  • dc motor speed increase, CEMF (counter electromotive force) increases
    • high starting torque because of lack of CEMF at the begining
  • two types of dc motors
    • permanent magnet dc motor
    • field wound dc motors
  • parallel wound dc motor (shunt motor)
    • field coils parallel with armature wiring
    • CEMF generated by armature does not effect the flow of current through the field coil
    • stable speed, low starting torque
    • fan blower motor
  • control speed of dc motors
    • variable electrical resistance
    • multiple shunt windings
    • PWD
  • commercial motor vehicle safety association (CMVSA)
  • battery isolation switches prevents batteries from discharging while the truck is parked
    • fused has to be added to protect constant power accessories
      • crack engine with the switches is open, or to have bad ground
  • install parallel-connected capacitor to reduce static noise
  • vehicle tracking system
    • satelite tracking system, (global positioning system, GPS)
    • communication component (digital satelite uplink)
  • truck data monitoring
  • tire pressure control system
    • based on road contact surface
      • less pressure - large - more traction & heat
    • vale pack box recieve control signal to add or discharge air from rear wheels
  • truck position sensing
    • collision warning system (CWS) (front-end, turn off @ 15mph)
    • adaptive cruise control (ACC)
    • collision mitigating system (CMS) (rear-end, turn off @ 15mph)
  • meritor wabco abs
    • electronic stability control (ESC)
    • roll stability control (RSC)
    • automatic traction control (ATC)
  • windshield wiper control system
    • the park contacts supply current to the motor after the wiper is turned off, allowing the motor to continue operating until the wipers reach the park position (@ lower moulding edge of the windshield)
  • gauges and sending units
    • direct acting gauges
      • speedometer (road speed) - transmision output shaft speed
      • tachometer (engine rpm) - fuel pump or camshaft speed
    • indirect acting gauges
  • starting circuit starting