Basic Controls of Your Vehicle
To drive a vehicle safely, you must be able to control its speed and direction. Safe operation of a commercial vehicle requires skill in:
- Backing safely.
Fasten your seat belt when on the road. Apply the parking brake when you leave your vehicle.
2.2.1 – Accelerating
Don’t roll back when you start. You may hit someone behind you. If you have a manual transmission vehicle, partly engage the clutch before you take your right foot off the brake. Put on the parking brake whenever necessary to keep from rolling back. Release the parking brake only when you have applied enough engine power to keep from rolling back. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be applied to keep from rolling back.
Speed up smoothly and gradually so the vehicle does not jerk. Rough acceleration can cause mechanical damage. When pulling a trailer, rough acceleration can damage the coupling.
Speed up very gradually when traction is poor, as in rain or snow. If you use too much power, the drive wheels may spin. You could lose control. If the drive wheels begin to spin, take your foot off the accelerator.
2.2.2 – Steering
Hold the steering wheel firmly with both hands. Your hands should be on opposite sides of the wheel. If you hit a curb or a pothole (chuckhole), the wheel could pull away from your hands unless you have a firm hold.
2.2.3 – Stopping
Push the brake pedal down gradually. The amount of brake pressure you need to stop the vehicle will depend on the speed of the vehicle and how quickly you need to stop. Control the pressure so the vehicle comes to a smooth, safe stop. If you have a manual transmission, push the clutch in when the engine is close to idle.
2.2.4 – Backing Safely
Because you cannot see everything behind your vehicle, backing is always dangerous. Avoid backing whenever you can. When you park, try to park so you will be able to pull forward when you leave. When you have to back, here are a few simple safety rules:
- Start in the proper position.
- Look at your path.
- Use mirrors on both sides.
- Back slowly.
- Back and turn toward the driver’s side whenever possible.
- Use a helper whenever possible.
- These rules are discussed in turn below.
Start in the Proper Position. Put the vehicle in the best position to allow you to back safely. This position will depend on the type of backing to be done.
Look at Your Path. Look at your line of travel before you begin. Get out and walk around the vehicle. Check your clearance to the sides and overhead, in and near the path your vehicle will take.
Use Mirrors on Both Sides. Check the outside mirrors on both sides frequently. Get out of the vehicle and check your path if you are unsure.
Back Slowly. Always back as slowly as possible. Use the lowest reverse gear. That way you can more easily correct any steering errors. You also can stop quickly if necessary.
Back and Turn Toward the Driver’s Side. Back to the driver’s side so you can see better. Backing toward the right side is very dangerous because you can’t see as well. If you back and turn toward the driver’s side, you can watch the rear of your vehicle by looking out the side window. Use driver-side backing–even if it means going around the block to put your vehicle in this position. The added safety is worth it.
Use a Helper. Use a helper when you can. There are blind spots you can’t see. That’s why a helper is important. The helper should stand near the back of your vehicle where you can see the helper. Before you begin backing, work out a set of hand signals that you both understand. Agree on a signal for “stop.”
2.3 – Shifting Gears
Correct shifting of gears is important. If you can’t get your vehicle into the right gear while driving, you will have less control.
2.3.1 – Manual Transmissions
Basic Method for Shifting Up. Most heavy vehicles with manual transmissions require double clutching to change gears. This is the basic method:
- Release accelerator, push in clutch and shift to neutral at the same time.
- Release clutch.
- Let engine and gears slow down to the rpm required for the next gear (this takes practice).
- Push in clutch and shift to the higher gear at the same time.
- Release clutch and press accelerator at the same time.
Shifting gears using double clutching requires practice. If you remain too long in neutral, you may have difficulty putting the vehicle into the next gear. If so, don’t try to force it. Return to neutral, release clutch, increase engine speed to match road speed, and try again.
Knowing When to Shift Up. There are two ways of knowing when to shift:
Use Engine Speed (rpm). Study the driver’s manual for your vehicle and learn the operating rpm range. Watch your tachometer, and shift up when your engine reaches the top of the range. (Some newer vehicles use “progressive” shifting: the rpm at which you shift becomes higher as you move up in the gears. Find out what’s right for the vehicle you will operate.)
Use Road Speed (mph). Learn what speeds each gear is good for. Then, by using the speedometer, you’ll know when to shift up.
With either method, you may learn to use engine sounds to know when to shift.
Basic Procedures for Shifting Down
- Release accelerator, push in clutch, and shift to neutral at the same time.
- Release clutch.
- Press accelerator, increase engine and gear speed to the rpm required in the lower gear.
- Push in clutch and shift to lower gear at the same time.
- Release clutch and press accelerator at the same time.
- Downshifting, like upshifting, requires knowing when to shift. Use either the tachometer or the speedometer and downshift at the right rpm or road speed.
Special conditions where you should downshift are:
Before Starting Down a Hill. Slow down and shift down to a speed that you can control without using the brakes hard. Otherwise the brakes can overheat and lose their braking power.
Downshift before starting down the hill. Make sure you are in a low enough gear, usually lower than the gear required to climb the same hill.
Before Entering a Curve. Slow down to a safe speed, and downshift to the right gear before entering the curve. This lets you use some power through the curve to help the vehicle be more stable while turning. It also allows you to speed up as soon as you are out of the curve.
2.3.2 – Multi-speed Rear Axles and Auxiliary Transmissions
Multi-speed rear axles and auxiliary transmissions are used on many vehicles to provide extra gears. You usually control them by a selector knob or switch on the gearshift lever of the main transmission. There are many different shift patterns. Learn the right way to shift gears in the vehicle you will drive.
2.3.3 – Automatic Transmissions
Some vehicles have automatic transmissions. You can select a low range to get greater engine braking when going down grades. The lower ranges prevent the transmission from shifting up beyond the selected gear (unless the governor rpm is exceeded). It is very important to use this braking effect when going down grades.
2.3.4 – Retarders
Some vehicles have “retarders.” Retarders help slow a vehicle, reducing the need for using your brakes. They reduce brake wear and give you another way to slow down. There are four basic types of retarders (exhaust, engine, hydraulic, and electric). All retarders can be turned on or off by the driver. On some vehicles the retarding power can be adjusted. When turned “on,” retarders apply their braking power (to the drive wheels only) whenever you let up on the accelerator pedal all the way.
Because these devices can be noisy, be sure you know where their use is permitted.
Caution. When your drive wheels have poor traction, the retarder may cause them to skid. Therefore, you should turn the retarder off whenever the road is wet, icy, or snow covered.
Test Your Knowledge
- Why should you back toward the driver’s side?
- If stopped on a hill, how can you start moving without rolling back?
- When backing, why is it important to use a helper?
- What’s the most important hand signal that you and the helper should agree on?
- What are the two special conditions where you should downshift?
- When should you downshift automatic transmissions?
- Retarders keep you from skidding when the road is slippery. True or False?
- What are the two ways to know when to shift?
These questions may be on the test. If you can’t answer them all, re-read subsections 2.2 and 2.3.