1 Unit 5: Measuring pressure, treads, and other vehicle dimensionsMeasuring and related math for future Truckers - II Unit 5: Measuring pressure, treads, and other vehicle dimensions Created by Leecy Wise for Utah State University-Eastern Campus, Blanding, UT, 2014 © Utah State University-Eastern Campus: Blanding, 2014
2 Please use your mouse to click through each slidePlease use your mouse to click through each slide. That will allow animations and quizzes to play correctly. Use the back arrow key on your keyboard or the back arrow icon at the bottom left part of each slide to move to previous slides. Move your cursor here to use back arrow
3 Road humor When you are laughing, you are learning, so laugh, laugh, laugh! Transport Topics: The Newspaper of Trucking and Freight Transportation
4 Why do truckers need math?If you drive your own car or pick-up, you might want to use math in different ways. You might want to know what kind of mileage you are getting, or the number of miles you need to travel, or the amount of time it will take to get from one place to another, or how safe you are on the road. You might even want to keep track of your expenses and create a budget for maintaining your vehicle.
5 A commercial trucker does not have those optionsA commercial trucker does not have those options. A commercial trucker must use math for those reasons and many others. Truckers must be able to handle financial transactions, complete log reports, measure loads, determine road characteristics, convert measurements, apply formulas, and much, much more. They must also be able to solve problems both on the job and on exams. To commercial truckers, math is a critical skill. It can be just as important sometimes as being able to drive in challenging weather.
6 Heavy equipment operators also need to know the math that relates to their environments. Other units in this series, Angles and Gradients, work with measuring angles related to pitch or inclination. Knowing how to measure the degree of pitch on the road or on heavy equipment can avoid tragic accidents from happening on work sites. Be sure to cover that unit so that you can be sure that you and others are safe in a dangerous environment.
7 This unit will work with you to develop the following skills:Maintaining healthy tire performance: pressure and treads. Maintaining correct pressure in brake systems. Maintaining correct oil pressure. Math: Converting English measurements into the metric system; Measuring circumference and diameter
8 I. Handling pressure systems
9 Pressure issues are especially important as they relate to your tires, oil system, and brakes. Checking the pressure in all systems will avoid tragedies on the road. What is pressure? Pressure is the force experienced by something that comes in contact with it. Think about a pressure cooker whose steam pressure on food tenderizes it in very little time. Pop a balloon, and you will release the air pressure that kept the rubber extended so that anyone could bat it back and forth with a friend.
10 You experience pressure from your blood in your arterial walls as the heart pumps it through from the heart. You can measure how much pressure is running through your system with gauges (measuring tools) that are placed on your arm. If one’s blood pressure is off, a person’s whole system is off. The body doesn’t operate efficiently and may eventually break down.
11 The same is true of how pressure affects vehiclesThe same is true of how pressure affects vehicles. If pressures is not applied correctly in your vehicle, it will not steer or function well, or your brakes will fail you. In that case, both you and your vehicle will be in trouble. Air pressure is used in many industrial systems to force parts to operate. Air is compressed and increased until it provides enough pressure to make things move. Pressure gauges show you how much pressure is being applied. Every vehicle has standards for pressure measurements. Get to know what those standards are for your vehicle before you operate it.
12 Pressure is measured in PSI units.PSI means Pounds Per Square Inch. Gauges measure how much pressure is applied to every square inch of something: tire walls, oil lines, brake lines, and more. In the figure above, PSI is shown in red. The black numbers express measurements (kPa) in other parts of the world This is one square inch
13 A. Tire Pressure Tires run on air pressure. Most tires drop about 1 PSI of pressure monthly. That means one pound for every square inch of the tire. Changing seasons will also reduce tire pressure, usually at the rate of 1 PSI per 10 degrees of temperature change. For example, a tire that reads 31 PSI at 30 degrees might read 35 PSI at 70 degrees. The only way to address these changes is to check your tire pressure often and at regular intervals. You will be rewarded for your efforts with better fuel economy and more even tread wear.
14 The tire sidewall will give you the maximum (not the recommended) PSI number for that tire. Even the recommended pressure setting for a loaded truck will result in a grossly overinflated tire when the truck is not loaded. Make sure you know the ideal PSI for tires on your vehicle under all conditions: loaded, unloaded, under hot and cold temperatures, and in different road conditions. Go to – Read about proper tire inflation with lots of examples.
15 B. Checking Oil PressureYou will need to measure pressure in other systems that run your vehicle effectively, like your oil system and your brake system. As you check your vehicle before and during travel, you will need to remain aware of what your gauges say. B. Checking Oil Pressure Oil pressure should come up to normal within seconds after engine is started. The Engine Oil Pressure gauge will have a higher PSI (pounds per square inch) when the oil is cold. As the engine warms up, the PSI will fall. Normal readings run from 30 to 75 PSI.
16 C. Air Brake Pressure SystemIt is hard to say which system in your vehicle is the most important. Surely, if you brakes don’t work, you and everyone ahead of you are in trouble. Your brakes are critical to driving safely! If your vehicle has an air brake system, you will need to know how pressure affects your brakes. Air brakes run on air pressure.
17 Refer to this image as you cover the next few slides.
18 There are many parts to your brake systemThere are many parts to your brake system. Following are a few to keep in mind. Air Compressor The air compressor pumps air into the air storage tanks (reservoirs). The air compressor is connected to the engine through gears or a v-belt. The compressor may be air cooled or may be cooled by the engine cooling system. It may have its own oil supply or be lubricated by engine oil. If the compressor has its own oil supply, check the oil level before driving.!
19 Air Compressor Governor The compressor governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level (around 125 PSI), the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure (around 100 PSI), the governor allows the compressor to start pumping again. Air pressure should build from 50 to 90 PSI within 3 minutes. Watch your gauges. Build air pressure to the governor cut-out (usually around PSI). Know your vehicles requirements for pressure guidelines.
20 Air Governor Explanation https://www. youtube. com/watchAir Governor Explanation https://www.youtube.com/watch?v=9Vb32PL1PVU Allow a few seconds for the video to load.
21 Application Pressure GaugesApplication gauge Application Pressure Gauges All vehicles are equipped with a pressure gauges to indicate the amount of air pressure in the main reservoir system. These gauge are mounted in the cab, usually on the dashboard. Common operating pressures are 85 PSI to 105 PSI and 105 PSI to 125 PSI, depending on the system. Monitoring gauges will alert the driver to any unusual changes in pressure. This gauges shows how much air pressure you are applying to the brakes. If you have to increase the application pressure to hold the same speed means the brakes are fading. You should slow down and use a lower gear. Go to the next slide to watch a movie clip showing exactly how the Air Compressor Governor works
22 Checking Brake Air Pressure through the Pedal You put on the brakes by pushing down the brake pedal. (It is also called the foot valve or treadle valve.) Pushing the pedal down harder applies more air pressure. Letting up on the brake pedal reduces the air pressure and releases the brakes. Releasing the brakes lets some compressed air go out of the system, so the air pressure in the system is reduced. It must be made up by the air compressor. Pressing and releasing the pedal unnecessarily can let air out faster than the compressor can replace it. If the pressure gets too low, the brakes won't work.
23 The need for increased pressure can also be caused by brakes out of adjustment, air leaks, or mechanical problems. A low air pressure warning signal is required on vehicles with air brakes. The warning signal you can see must come on before the air pressure in the tanks falls below 60 psi. (Or one half og the compressor governor cut-out pressure on older vehicles.) The warning is usually a red light. A buzzer may also come on. Go to the next slide to watch a clip on how the whole Air Brake system works.
24 Full explanation on how air brakes work https://www.youtube.com/watch?v=UuajFbUNydo Allow a few seconds for the video to load.
25 Tire Pressure Monitoring and Inflation Maintenance - 2010 StudyII. TIRE TREAD ISSUES Tires are the cause of 53.5 % of roadside breakdowns, according (Heavy Duty Trucking magazine). From 2007 to 2009, they were also the second leading cause of roadside inspection citations after brakes, as reported by the Commercial Vehicle Safety Alliance (CVSA). Read more amazing statistics related to tire maintenance and inspection by clicking on the link below. Tire Pressure Monitoring and Inflation Maintenance Study Tires represent the highest vehicle operating cost after fuel among fleets in the US.
26 As you now know, too much or too little air pressure can damage a tire in very little time. Bad wear is another major reason for tire damage. You need at least 4/32-inch tread depth in every major groove on front tires. You need 2/32 inch on other tires. No fabric should show through the tread or sidewall.
27 What does 4/32-inch tread depth or 2/32 inch depth meanWhat does 4/32-inch tread depth or 2/32 inch depth mean? When you see a fraction like or , always look at the number bellow the line first. That number always tells you how many PARTS represent the whole. It is called the denominator. The top number is called the numerator. It tells you how many parts your are talking about. nominator denominator
28 In the fractions above, one inch (the whole) has been divided into 32 parts. You are still talking about one whole inch as your reference. The denominator at the bottom, tells you how many parts you are working with. Now look at the image of one inch below. How many parts (divisions) do you see dividing the space of 1 inch?
29 If you said “16,” you are absolutely correctIf you said “16,” you are absolutely correct! In this image, one inch is divided into 16 parts. If you are measuring a space that takes up two of those 16 parts, how would you express the fraction? Write it down and click when you are ready. 16 parts If you wrote , you got it! That is correct! 2 parts out of 16, is written as a fraction:
30 Now, let’s divide the inch into 32 sectionsNow, let’s divide the inch into 32 sections. Write a new fraction showing 4 parts of the new denominator of 32. Click to check your answer! 4 parts out of 32 parts
31 Is bigger or smaller than ?What do you notice when you compare the space occupied by these two different fractions? Look at the space occupied by each. Is bigger or smaller than ?
32 Your eyes do not deceive youYour eyes do not deceive you. Which is more, twenty five cents or a quarter? As they say, six one, half a dozen the other. They are just two different ways of saying the same thing. is the same amount as
33 and are equivalent fractions.When two different fractions say the same thing, they are called equivalent fractions. Now let’s go back to measuring your tire treads. You need at least 4/32-inch tread depth in every major groove on front tires. You need 2/32 inch on other tires. and are equivalent fractions.
34 Use any of the many types of gauges to measure your tire treads.4/32-inch tread depth in every major groove on front tires 2/32 inch on other tires. Use any of the many types of gauges to measure your tire treads.
35 If you don’t have a gauge to measure the treads of your tire, you can dig into your purse or pocket and grab a penny or a quarter. CLICK HERE to see how you can estimate the wear on your tires with coins.
36 Sometimes, gauges will state results in centimeters instead of inchesSometimes, gauges will state results in centimeters instead of inches. The US is one of the only places in the world that uses the English System for measuring distance quantities, like inches, feet, yards, and miles. Other countries use the metric system, stating results in centimeters, meters, and kilometers. Knowing how to measure in both systems will really help you working with tires. It will also help you work with tools and parts in building and other occupations.
37 How often have you bought a nut that didn’t fit a bolt because they were cut from different systems?Both the metric system and the US English system do a fine job of measuring lengths, volumes, and weights. However, they don’t mix. That is why you must know how to convert from one system to another. That is very helpful, especially if you are on the road and have only your calculator, if that, to help you out.
38 III. THE METRIC SYSTEM 1 meter 1 yardThe metric system is actually much easier to work with than our US system. Everything in the metric system is based on TEN and multiples of ten. All measurements will be divided or multiplied by 10, the perfect number! The basic unit in the metric system is the METER. You’ll find the word “meter” as part of all metric measures as you will see. The closest measurement to the meter in the US system is the YARD. One meter is a little longer than one yard. 1 meter 1 yard One meter is made up of 100 centimeters or 1 hundredths (1/100) of a meter. One yard is made up of 36 inches.
39 How does a meter compare to a yard?1 meter = yards If you are converting from meters to yards (larger to smaller unit), multiply the number of meters by Going from a bigger unit (meter) to smaller one (yard), multiply. There will be more yards than meters. Bigger units to Smaller Units Multiply m y x 3 m = 3 m x = y 1 meter 1 yard
40 Smaller units to Larger Units Divide1 meter = yards If you are converting yards to meters, divide the number of yards by Smaller units to Larger Units Divide y m ÷ 3 y = 3 y ÷ = m m y
41 If you don’t need a precise calculation, you can convert these units faster, both on paper and on a calculator, by rounding off the numbers. 1 meter = approximately 1.09 yards The answers you get will be close enough to judge the distances.
42 When you are done, click to check your answers.Use the rounded-off conversion units. They will be close to the exact measurements. Check it out. Imagine that you are measuring or reporting the size of shipping containers. Convert their measurements in the metric system. 2.5 y = __ m 3 y = __ m 4.2 y = __ m Imagine that you get a shipping label with metric units. Convert the measurements into the US System. 1.5 m = __ y 0.7 m = __ y 2 m = __ y When you are done, click to check your answers.
43 When you are done, click to check your answers.Use the rounded-off conversion units. They will be close to the exact measurements. Check it out. Imagine that you are measuring or reporting the size of shipping containers. Convert their measurements in the metric system. 2.5 y = m 3 y = m 4.2 y = m Imagine that you get a shipping label with metric units. Convert the measurements into the US System. 1.5 m = y 0.7 m = y 2 m = y When you are done, click to check your answers.
44 To practice converting between yards and meters, complete the worksheet and check your answers when you are done. Use the more exact measurement for your answers. 1 meter = yards Click here for a reference table to check your answers. Round off your numbers. 2 y = _____ m 16 m = _____ y 6.5 y = _____ m 21 m = _____ y 5 m = _____ y 4.5 y = _____ m 12 m = _____ y 22 y = _____ m
45 2 y = 1.83 m 16 m = 17.5 y 6.5 y = 5.94 m 21 m = y 5 m = 5.47 y 4.5 y = 4.15 m 12 m = y 22 y = m
46 Now let’s get a little smaller since we are going to measure tire treads. One meter is made up of 100 centimeters or 1 hundredths (1/100) of a meter. The word “Centi” means one hundredth. On the other hand, one yard is made up of 36 inches. One inch is bigger than one centimeter as you can see. Compare the distance between inches, at the top, and centimeters, at the bottom. 1 inch = 2.54 centimeters inches centimeters
47 Inches to Centimeters Practice Inches to Centimeters Answer SheetClick on the Worksheet below to practice converting inches into centimeters. Tip: Remember that when you are converting from a larger unit into a smaller unit, you will MULTIPLY. 1 in = 2.54 cm 2 in = 2 x 2.54 = 5.08 cm 3.5 in = 3.5 x 2.54 = 8.89 cm Inches to Centimeters Practice Inches to Centimeters Answer Sheet Note: the practice sheet has copies of rulers that show both inches and centimeters. Cut out a ruler or use your own to measure.
48 You need at least 4/32-inch tread depth in every major groove on front tires. You need 2/32 inch on other tires. You can convert these fractions (inches) to centimeters in 2 ways: You can multiply the fraction by the decimal. OR You can change the fraction into a decimal and then multiply.
49 Method 1- Multiply the fraction by the decimal.1 in = 2.54 cm To multiply, write the fraction as it is. Then write a number 1 under the decimal to make it into a fraction. (Any number divided by one stays the same!) (Click) Next multiply the numerators and the denominators. (Click) Finally, turn the answer into a decimal. Divide the numerator by the denominator. (Click) 10.16 ÷ 32 = cm
50 Method 2 - Change the fraction into a decimal and then multiplyIn the first method, you changed a fraction into a decimal. You divided 10.56/32 to get cm! Do the same with this fraction. Once you turned the fraction into a decimal, all you have to do is multiply! (1 in = 2.54 cm) 0.125 x 2.54 = cm As you can see, you get the same answer using either method. Use the one that is easiest for you to remember. = 4 ÷32 = 0.125
51 To review this process, go to http://www. sophia. To review this process, go to inches-and-centimeters--2 To see the actual division process of turning 4/32 into a decimal, go to = 4 ÷32 = 0.125
52 4/32-inch = 0.3175 cm on your front tires.And there you have it! 4/32-inch = cm on your front tires. Your remaining tires should measure at least 2/32 inch. Use either method to convert that amount into inches. On the other hand, think about it.
53 2/32 is half of 4/32. The fist fraction takes up 2 parts out of 32. The second takes up 4 parts out of 32, twice the number of parts. Remember ? 4/32-inch tread depth in every major groove on front tires 2/32 inch on other tires.
54 2/32 is half of 4/32. Since you know that 4/32 = cm, all you need to do is divide that number by 2! cm ÷ 2 = cm Your remaining tires should measure at least cm If you would like more practice converting measures into the metric system, as your instructor for more worksheets.
55 IV. STEERING ISSUES Measuring inches and centimeters will also help you identify steering problems. Tire pressure and other tire issues really affect your steering. Steering wheel play also causes problems. A steering wheel play of more than 10 degrees can make it hard to steer. 10 degrees represents approximately 2 inches movement at the rim of a 20-inch steering wheel.
56 You can recognize a movement of two inches along the rim of a steering wheel. Notice your hand moving the steering wheel 2 in in either direction before the turn begins. Convert those two inches into centimeters. When you are done, click to check your answer. inches centimeters 1 in = cm 2 in = 2 x 2.54 = 5.08 cm inches centimeters
57 Your CDL Manual states, “A steering wheel play of more than 10 degrees (approximately 2 inches movement at the rim of a 20-inch steering wheel) can make it hard to steer.” The easiest way to measure of a steering wheel is to measure its diameter. What is a diameter? A diameter is a line that runs through the center of a circle connecting two points along the rim of the circle. The rim of a circle (steering wheel) is called a circumference. Click to see both measurements. circumference diameter
58 You can measure a diameter starting at any point along the circumference and drawing a line through the middle. All of the blue lines running through the center of the circle measure the same. They are all diameters.
59 The manual says, “A steering wheel play of more than 10 degrees (approximately 2 inches movement at the rim of a 20-inch steering wheel) can make it hard to steer.” (Click to see the diameter) How many centimeters is a 20 in steering wheel? Do the math and click to check your answer! 20 in 2 in 1 in = cm 20 in = 20 x 2.54 = cm
60 Tire problems also result from the following conditions:Too much or too little air pressure. Cuts or other damage. Tread separation. Dual tires that come in contact with each other or parts of the vehicle. Mismatched sizes.
61 Radial and bias-ply tires used together. Cut or cracked valve stems.R2-grooved, recapped, or retreaded tires on the front wheels of a bus. These are prohibited. To review common tire issues in trucking, go to
62 Steering problems can also result from…Missing nuts, bolts, cotter keys, or other parts. Bent, loose, or broken parts, such as steering column, steering gear box, or tie rods. If power steering equipped, check hoses, pumps, and fluid level; check for leaks. Conclusion? Inspect your vehicle and check for common issues to avoid accidents and delays on your trip! Your CDL Manual will discuss a number of other issues to double-check before driving on and off roads and highways.
63 TAKE A FINAL QUIZ TO REVIEW SOME OF WHAT YOU’VE LEARNED.Click on the link below. A Web page will open in your browser, with links to three quizzes. When you complete all answers. If you have a lower score than you want, review this presentation, then take the quiz again until you are sure of all answers. Measurements II Quiz inches centimeters
64 It is important that you keep practicing math skills using the resources in this series and those that your instructor will give you. Remember that practice makes perfect, and it keeps your skills sharpened so you can slice right through problems and road challenges!
65 CONGRATULATIONS! If you completed Units 1-5, you are now ready to enter training to earn your CDL! Happy trucking!
66 Math and TERMINOLOGY for future TruckersThis series was produced by Utah State University-Eastern Campus, CDL Program. All content, with exception of links and references to online resources, is original and tailored to the needs of students hoping to succeed in earning their Commercial Drivers License. All images are either original or taken from the following resources: Utah CDL Handbook Transport Topics: The Newspaper of Trucking and Freight Transportation- Utah State University-Eastern Campus, Blanding, UT: All Rights Reserved, 2014 © Utah State University-Eastern Campus: Blanding, 2014