By Fatskills Exam Guides Team — the exam nerds behind 28,500+ quizzes and 2.1M practice questions across 500+ global exams.
Mechanical aptitude is tested on many firefighter exams. This guide will familiarize you with commonly tested concepts by presenting definitions, study tips, and sample test questions for basic mechanical devices and systems. Firefighters use mechanical devices every day: simple hand tools such as axes and wrenches, as well as more complex systems such as pumps and internal combustion engines. The ability to understand and use mechanical concepts is critical to a firefighter's job. If your exam includes a section on mechanical aptitude, it may cover topics with which you are very familiar, as well as some that are new. Regardless of your background, understanding the concepts in this guide will benefit you both for the exam and in your career as a firefighter. After an introduction to mechanical aptitude questions, this guide summarizes the most commonly tested mechanical devices and mechanical systems. It also suggests ways in which you can further improve your knowledge of mechanical devices and related scientific and mathematical knowledge. Finally, it gives you an opportunity to review what you've learned by presenting a sample mechanical aptitude section like those found on firefighter exams. What Mechanical Aptitude Questions Are Like Mechanical aptitude questions tend to cover a wide range of topics. The questions will usually be multiple choice with four or five possible answers. Some questions may require previous knowledge of the topic so it is a good idea to study this guide well!and other questions will include all of the information you will need. Some questions will require the identification of various mechanical tools or devices. Some of the types of mechanical devices that may appear on the examand are covered in this guide include hand tools, gears, pulleys, levers, fasteners, springs, valves, gauges, and pumps. In addition to individual mechanical devices, the exam may test your knowledge of various systems, or combinations of mechanical devices. A common example of a mechanical system is the internal combustion engine of an automobile. A typical mechanical aptitude question will look something like this: Which of the following is a common component of an internal combustion engine? a. a piston b. compass c. hammer d. hydraulic jack The answer is a, a piston. A compass is used to determine a direction on a map. A hammer is used to drive nails. A hydraulic jack is used to lift heavy items. What Is a Mechanical Device? A mechanical device is a tool invented to make a given task easier. For example, you could drive a nail into a piece of wood with a rock. However, a long time ago, someone who spent most of his time building things with wood figured out that it would be a lot more efficient if he had something easier to hold on to than a rock. He thought that a long slender handle might be nice and that a hard piece of metal for striking the nail would provide more accuracy and would not damage the wood as easily. Thus was born the hammer. Most mechanical devices were invented in the same manner: people looking for easier ways to perform their everyday jobs. Some mechanical devices are thousands of years old, such as the lever, the wheel, and many hand tools. Other more complex devices, such as pumps and valves, were invented more recently. Many times the idea of a new mechanical device exists but the technology to actually make it does not. For example, many years before the pump was invented, people probably discussed the need for an easier way to move water from the river to the town on the hill. However, the technologies of the electric motor and casting of metal had not yet been invented, so the modern pump could not possibly have been invented at that time. Mechanical devices cover a wide range of types of tools. In general, they are tools that relate to physical work and are governed by mechanical forces and movements. You can usually see what they do and how they workas opposed to, say, a light switch or a battery, which are electrical devices. Some tools are used to directly accomplish a specific task, as when you use a hand saw to cut a piece of wood. Others, such as pulleys and gears, may be used indirectly to accomplish certain tasks that would be possible without the device but are easier with the device. Still others, such as gauges, only provide feedback information on the operation of other mechanical devices. You see and use mechanical devices many times each day, so there's no reason to be intimidated by a mechanical aptitude section on the exam. Commonly Tested Mechanical Devices The sections below review some of the mechanical devices that are most likely to appear on firefighter exams. Hand Tools Hand tools are defined as tools operated not by motors but rather by human power. There are many different types of hand tools including carpentry tools, automotive hand tools, and hand tools used specifically by firefighters. This guide cannot cover every conceivable hand tool, so it will be limited to tools used in everyday situations and those specific to firefightingthe ones you are most likely to be tested on. Some of the hand tools used by carpenters and other workers, including firefighters, are listed in the table on the next page, along with their most common uses and some examples of each kind. Some of the hand tools used in the automotive industry are listed below. Wrenches are used to tighten and loosen nuts and bolts. Examples include vice grips and box end, ratchet, crescent, and pipe wrenches. Mechanical jacks are used to lift cars so that tires can be changed. The jack in the trunk of your car is an example. In addition to the tools above, some hand tools are used specifically by firefighters (and sometimes by other workers as well): Ladders are used to access high areas. Firefighters use different kinds of ladders, including extension ladders and aerial ladders. Axes are used by firefighters to break down doors and walls and as prying tools. This tool is very similar to an ax used to chop firewood. Gears A gear is generally a toothed wheel or cylinder that meshes with another toothed element to transmit motion or to change speed or direction. Gears are typically attached to a rotating shaft turned by an outside energy source such as an electric motor or an internal combustion engine. Gears are used in many mechanical devices including automotive transmissions, carpenter's hand drills, elevator lifting mechanisms, bicycles, and carnival rides such as Ferris wheels and merry-go-rounds. Gears can be used in several different configurations. Two gears may be connected by directly touching each other, as in an automotive transmission. In this arrangement, one gear spins clockwise and the other rotates counterclockwise. Another possible configuration is to have two gears connected by a loop of chain, as on a bicycle. In this arrangement, the first gear rotates in one direction, causing the chain to move. Since the chain is directly connected to the second gear, the second gear will immediately begin to rotate in the same direction as the first gear. Many times a system will use two gears of different sizes, as on a ten-speed bicycle. This will allow changes in speed of the bicycle or machine. Problems about gears will always involve rotation, or spinning. The easiest way to approach test questions CARPENTER'S TOOLS Tool - Description/Function - Examples
Pulleys A pulley consists of a wheel with a grooved rim in which a pulled rope or cable is run. Pulleys are commonly used with ropes or steel cable to change the direction of a pulling force.
Pulleys are often used to lift things. For instance, a pulley could be attached to the ceiling of a room. A rope could be run from the floor, up through the pulley, and back down to a box sitting on the floor. The pulley would allow you to pull down on the rope and cause the box to go up. That is, the pulley caused a change in direction of the pulling force.
Another common use for a pulley is to connect an electric motor to a mechanical device such as a pump. One pulley is placed on the shaft of the motor, and a second pulley is placed on the shaft of the pump. A belt is used to connect the two pulleys. When the motor is turned on, the first pulley rotates and causes the belt to rotate, which in turn causes the second pulley to rotate and turn the pump. This arrangement is very similar to the previous example of a bicycle chain and gears.
You may have seen pulleys used in a warehouse to lift heavy loads. Another use for a pulley is on a large construction crane. The cable extends from the object being lifted up to the top of the crane boom, across a pulley, and back down to the electric winch that is used to pull on the cable. In this situation the pulley again causes a change in direction of the pulling force, from the downward force of the winch that pulls the cable to the upward movement of the object being lifted. Levers A lever is a very old mechanical device. A lever typically consists of a metal or wooden bar that pivots on a fixed point. The object of using a lever is to gain a mechanical advantage. Mechanical advantage results when you use a mechanical device in order to make a task easier; that is, you gain an advantage by using a mechanical device. A lever allows you to complete a task, typically lifting, that would be more difficult or impossible without the lever.
The most common example of a lever is a playground seesaw. A force (a person's weight) is applied to one side of the lever, which causes the weight on the other side (the other person) to be lifted. However, since the pivot point on a seesaw is in the center, each person must weigh the same or things do not work well. You see, a seesaw is a lever with no mechanical advantage. If you push down on one side with a weight of 10 pounds you can only lift a maximum of 10 pounds on the other side. This is no great advantage.
This brings us to the secret of the lever: in order to lift an object that is heavier than the force you want to apply to the other side of the lever, you must locate the pivot point closer to the object you want to lift. If two 50-pound children sit close to the center of the seesaw, one 50-pound child close to the end of the board on the other side will be able to lift them both. Test questions about levers will typically require a bit of math (multiplication and division) to solve the problem. There is one simple concept which you must understand in order to solve lever problems: the product of the weight to be lifted times the distance from the weight to the pivot point must be equal to the product of the lifting force times the distance from the force to the pivot point. Stated as an equation, w × d1 = f × d2. For example, Bill has a 15-foot long lever and he wants to lift a 100-pound box. If he locates the pivot point 5 feet from the box, leaving 10 feet between the pivot point and the other end of the lever where he will apply the lifting force, how hard must he press on the lever to lift the box? Use the lever formula, w × d1 = f × d2. The weight of 100 pounds times 5 feet must equal 10 feet times the force: 100 × 5 = 10 × force. Using multiplication and division to solve for the force, you get 50 pounds of force that Bill must apply to the lever to lift the box. Fasteners A mechanical fastener is as any mechanical device or process used to connect two or more items together. Typical examples of fastening devices are bolts, screws, nails, and rivets. Processes can be used to mechanically join items together including gluing and welding. There are also unique mechanical fasteners such as ''hook and loop," which consist of two tapes of material with many small plastic hooks and loops that stick together. Children's sneakers often use such fastening tape instead of laces. Springs A spring is an elastic mechanical device, normally a coil of wire, that returns to its original shape after being compressed or extended. There are many types of springs including the compression coil, spiral coil, flat spiral, extension coil, leaf spring, and torsional spring. Springs are used for many applications such as car suspensions (compression coil and leaf springs), garage doors (extension coil and torsion springs), wind-up clocks (flat spiral and torsion springs), and some styles of ballpoint pens (compression coil). In the kinds of questions you're likely to be asked on the firefighter exam, you can assume that springs behave linearly. That is, if an extension spring stretches one inch under a pull of ten pounds, then it will stretch two inches under a pull of twenty pounds. In real life, if you pull too hard on a spring, it will not return to its original shape. This is called exceeding the spring's elastic limit. Your exam is not likely to deal with this type of spring behavior. If several springs are used for one application, they can be arranged in one of two ways: in series or in parallel. The easiest way to remember the difference is that if the springs are all hooked together, end to end, then you have a series of springs. The other option is for the springs not to be hooked together but to be lined up side by side, parallel to each other. If two springs are arranged in series, they will stretch much farther than the same two springs arranged in parallel under the same pulling force. This is because in series, the total pulling force passes through both springs.
If the same springs are arranged in parallel, the pulling force is divided equally with half going through each spring. The key to solving spring problems is to draw a diagram of the arrangement, if one isn't already provided, and follow the pulling force through the system. Valves A valve is a mechanical device that controls the flow of liquids, gases, or loose material through piping systems. There are many types of valves including butterfly valves, gate valves, plug valves, ball valves, and check valves. A valve is basically a gate that can be closed or opened in order to permit the fluid or gas to travel in a particular direction. The type of exam question you are likely to see that involves valves will be one in which you must follow a piping flow diagram through several sets of valves. These problems are best approached by taking your time and methodically following each branch of the piping system from start to finish. Gauges Gauges are used to monitor various conditions and performance of mechanical machines such as pumps and internal combustion engines, as well as to monitor the surrounding atmospheric conditions which could indirectly affect a particular machine. Gauges are usually marked with the units they are measuring.
A few examples of different types of units are: Degrees Celsius or Fahrenheit for temperature gauges Pounds per square inch (psi) for pressure gauges Meters (or sometimes feet) for elevation gauges You must be very careful to recognize and understand the units of a gauge that appears in a test question. For instance, a temperature gauge (commonly called a thermometer) could use either degrees Fahrenheit or degrees Celsius. Mistakes on units can cause major problems, so be careful! Gauges are sometimes marked with warnings about limits of safe operation. For instance, an oil pressure gauge on an internal combustion engine may show a maximum safe working pressure of 15 psi. If you're asked about the safe operation of a device with a gauge on it, you should pay careful attention to any markings that show such a limit. Pumps A pump is a device used to transfer a liquid or a gas from one location, through a piping system, to another location. There are many different types of pumps, including centrifugal pumps, positive displacement pumps, metering pumps, diaphragm pumps, and progressive cavity pumps. Generally speaking, a working pump consist of the pump itself (case, bearings, impeller, seals, shaft, base, and other components) and an outside energy source. The outside energy source could be an electric motor, internal combustion engine, or battery to provide mechanical energy to the pump. This energy causes the inner workings of the pump to propel the liquid or gas through the piping system. The flow rate at which the liquid or gas is pushed through the piping system is typically measured by a flow meter in units of gallons per minute (gpm) or cubic feet per minute (cfm). Pumps are used for many purposes. Some examples include gasoline pumps used to pump the gasoline from a holding tank into your car, water pumps to transfer drinking water from a reservoir to your house or business, and industrial pumps used to move industrial fluids such as chemicals or waste products from one tank to another inside a plant. A car also uses pumps ATMOSPHERIC GAUGES Gauge - What It Measures - Units
Thermometer - temperature - degrees Fahrenheit or Celsius Barometer - atmospheric pressure - inches or millimeters of mercury Hygrometer - relative humidity - percentage of water in air MACHINE PERFORMANCE GAUGES
Systems That Use Mechanical Devices Many mechanical devices are actually a combination of several simple devices that work in conjunction to form a group of interacting mechanical and electrical components called a system. Some of the systems most likely to appear on the exam are discussed below. Internal Combustion Engines Internal combustion engines (ICEs) are commonly used to drive many mechanical devices. However, they are very complex mechanical devices themselves. ICEs are used in cars, trucks, construction equipment, and many other devices. They can be fueled by gasoline, diesel fuel, natural gas, or other combustible fossil fuels. An ICE is a system composed of dozens of individual mechanical (as well as electrical) systems. A few of the major systems within an ICE are discussed below. The Cooling System The purpose of the cooling system is to dissipate the heat generated by the engine. The system consists of a pump that moves the coolant, antifreeze, from the radiator through piping to the engine block, where it becomes hot, and then back out to the radiator where the liquid coolant is cooled. The Pistons, Tie Rods, and Crankshaft The pistons, tie rods, and crankshaft are all parts of the inner workings of an ICE. When the spark plug inside the engine cylinder ignites the fuel, the piston is forced downward. The piston is mechanically fastened to the tie rod, which is therefore also driven downward. The tie rod is attached to the crankshaft and applies a rotation to the crankshaft. The crankshaft has gears attached to it that are connected to other gears on the transmission. Eventually the power is transferred to the wheels of the car, the inner workings of the pump, or whatever device the ICE is driving. The Fuel Pump Fuel, typically gasoline or diesel fuel, is transferred from the tank to the engine by the engine's mechanical fuel pump. The Throttle Governor The throttle governor is a device in an ICE that uses a spring to reduce the flow of gas back to idle level when you take your foot off of the gas pedal. Automobiles and Other Vehicles An automobile is one of the most complex assemblies of mechanical devices in existence. The ICE is only one of many subsystems of mechanical devices on an automobile. A few of the other devices and systems are discussed below. The Brakes Automobile brakes are activated by pressing the brake pedal, which compresses a piston that forces hydraulic fluid through the brake line piping. The brake fluid presses against a set of mechanical calipers that squeeze the brake pads against the rotors. The rotation of the wheels is slowed by friction. Several springs are used to return the brake pedal and the calipers to their neutral position. The Steering Assembly The steering wheel is attached to a shaft with gears on it. The gears turn to rotate a series of levers that are connected by bolted connections. The levers then cause the wheels to turn. The Exhaust System The exhaust system includes a system of piping connected to the engine with welded joints. Several brackets are used to suspend the piping beneath the automobile. The engine's exhaust passes through the piping to the muffler, which is an acoustical chamber that reduces the engine noise. Bicycles A bicycle is not nearly as complex as an automobile. However, it too uses several mechanical devices.
Brushing up on Related Topics Some mechanical aptitude questions may require the use of math or science to determine the correct answer. This guide cannot cover all the possible questions you might be asked on the firefighter exam, but here are suggestions for ways to increase your knowledge of math, science, and general mechanical aptitude.
Math The required mathematical skills are primarily arithmetic (addition, subtraction, multiplication, and division) and geometry (angles and shapes). The arithmetic involved is almost always fairly simple. If you had trouble with arithmetic or geometry in your past schooling, you can brush up by reading up on basic applied math. If you still want more help, pull out your old high school math book or check out a math book from the library.
Science Science subjects such as physics, materials science, thermodynamics, and chemistry are confusing for some people, but they needn't be. Science is real, everyday life. You see science in action dozens of times every day. A car is stopped by brakes, which use friction (physics). A magnet adheres to the refrigerator due to the properties of the magnet and carbon steel of which the door is made (materials science). A pot of water boils when you set it on the stove and turn on the burner (thermodynamics). A tomato plant grows through the chemical reaction of sunlight, water, and food (chemistry). This guide has reviewed many of the scientific concepts that are involved in mechanical devices. Again, as with math, you may have science books from previous schooling that you can use to help you solidify your scientific knowledge. If not, the library is full of scientific resources. General Mechanical Aptitude Mechanical devices are such an integral part of everyday life that there are many real-life sources you can investigate to gain more knowledge of their design and use. A construction site is a great place to visit for a day to learn more about hand tools, cranes, pumps, and other devices. Ask the construction supervisor if you can take a tour. Another alternative would be to hang out at an automotive repair shop. Internal combustion engines, lifts, levers, and hand tools are only a few of the types of mechanical devices you could see in use. Yet another possibility would be to visit a local manufacturer in your town.
Examples include a foundry, a sheet metal fabricator, an automotive manufacturer, or a pump manufacturer. Look in the yellow pages under ''manufacturing" for possibilities.
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