2.1: Primary Controls
- Page ID
- 49437
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Engine Controls:
- Key Switch: Operates like a key switch in your car, it is a four position switch with the following positions. Older trucks will not have a start position, this will be replaced by a starter button.
- Accessory - In this position all electrical accessories will operate.
- Off - In this position the truck is off and no electrical accessories will operate.
- Run - This is the position the key will be in when the truck is running, all electrical accessories will operate.
- Start - This position is only used to start the truck, once started the key will automatically return to the run position.
- Starter Button: Used to start the engine, this is more common on older trucks.
- Cruise Control: Used to maintain a steady speed without using the accelerator pedal.
- Steering Wheel: Used to control the direction of the vehicle.
- Steering Wheel Adjustment: When unlocked the steering wheel can be tilted or telescoped for maximum driver comfort.
- Accelerator Pedal: Controls the vehicle’s speed by increasing fuel flow to the engine.
- Foot Brake Control Valve also referred to as the service brake, foot valve or treadle valve: Engages the service brakes to slow down or stop the vehicle.
- Clutch Pedal (for manual transmissions): Disengages the engine from the drivetrain to allow for shifting gears. The clutch pedal has four basic positions.
- Engage - When the pedal is fully released the clutch is engaged which means the engine is connected to the drive train.
- Free Play - The first ¾ - 2 inches of clutch travel before the clutch is disengaged. If the clutch pedal has no free play the clutch needs to be adjusted or replaced.
- Disengaged - When the clutch pedal is depressed past the free play to about 1 inch shot of the floor, at this point the engine is disconnected from the drive train.
- Clutch Brake - When the clutch pedal is fully depressed the clutch brake is engaged this stops the rotation of the transmission so that the truck can be put into first gear or reverse. Failure to engage the clutch brake will cause grinding when putting the truck in gear. Additionally depressing the clutch fully when shifting between gears can cause damage to the clutch brake.
- Transmission Controls:
- Shifter: Used to change gears in the transmission
- Range Selector: Located on the front of the shifter, used to switch between high and low range.
- Splitter: Used to split single gears between high and low also referred to as direct and overdrive. Splitters are found on 13, 15, and 18 speed transmissions, the color of the splitter determines the transmission: 13 speed is red, 15- speed is blue, and 18 speed is gray.
- Trailer Brake Control Valve also the hand valve or trolley valve: Engages the service brakes on the trailer only. The valve should never be used in place of the parking brake, improper use can cause the trailer to skid and possibly jackknife.
- Parking Brake Control Valve (Yellow): Used to operate the parking brakes on the tractor only, parking brakes should only be activated when the vehicle is at a complete stop.
- Trailer Air Supply Valve (Red): Used to supply air to the trailer to release the parking brakes. The valve should never be operated when no trailer is connected, if the trailer was to become disconnected the valve will close automatically.
- Antilock Brakes: Anti-lock Braking Systems (ABS) are designed to prevent the wheels from locking up during braking. This is crucial for maintaining steering control and reducing the risk of skidding, especially on slippery surfaces. ABS uses sensors to monitor wheel speed and, if it detects a potential lock-up, it modulates the brake pressure to allow the wheels to keep rotating. This system enhances vehicle safety by improving stopping distances and ensuring better vehicle stability and control under heavy braking conditions. ABS has been mandatory on all new commercial trucks in the U.S. since 1997.
- Auxiliary Brakes and Retarders: Auxiliary brakes and retarders on commercial trucks are additional systems designed to improve braking performance and reduce wear on the primary brakes. They are essential for maintaining control and safety, especially on long descents and in heavy traffic. Here's a breakdown:
1. Engine Brakes: These include systems like the Jake Brake (Jacobs Engine Brake), which modifies the engine's exhaust valve operation to create back pressure, slowing the vehicle by converting the engine into a power-absorbing air compressor.
2. Exhaust Brakes: These work by restricting the flow of exhaust gases, creating back pressure that slows the engine and the vehicle. This type of braking is less powerful than engine brakes but still effective in providing additional stopping power.
3. Retarders:
- Hydraulic Retarders: Use the resistance of a fluid, usually oil, to create a braking force. They are integrated into the transmission or driveline and provide continuous braking without relying on friction.
- Electric Retarders: Generate braking force through magnetic resistance. When activated, they create a magnetic field that slows down the drivetrain, providing smooth and consistent braking.
These systems help in maintaining vehicle control, especially in situations where the primary brakes might overheat or fail, thereby enhancing overall safety and extending the lifespan of the primary braking system.
- Differential Lock: The differential lock enables even power distribution between each drive tire on a single drive axle.
- Interaxle Differential Lock: The interaxle differential lock or power divider enables equal power to be distributed between each of the drive axles on a truck with two drive axles. Some trucks are equipped with both a power divider and differential locks.