Part 1. Preparation and safety
Objective
- Demonstrate the correct method of measuring using a dial indicator.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Dial indicators are used in many types of service jobs. They are particularly useful in determining run-out on rotating shafts and rotors.
- Run-out is the side-to-side variation of movement when a component is turned.
- Dial indicators normally have two separate scales. The needle is able to move numerous times around the outer scale. One full turn may represent 0.1" or 1mm. The small inner scale indicates how many times the outer needle has moved around its scale. In this way, the dial indicator is able to read movement of up to 2" or 1cm.
- Dial indicators can measure with an accuracy of 0.001" or 0.01mm.
- The type of dial indicator you use will be determined by the amount of movement you expect from the component you are measuring.
- They must be fitted so that there is no movement between the dial indicator and the component to be measured.
- Most dial indicator sets contain various attachments and support arms so they can be attached to the component. There are other attachments available. These attachments allow the dial indicator to be configured specifically for the measuring task.
- When attaching a dial indicator, keep support arms as short as possible. Make sure that all attachments are tightened to prevent unnecessary movement between the indicator and the component.
- Make sure the dial indicator pointer is positioned at 90º to the face of the component to be measured.
- Always read the dial, face or straight on. A view from the side can give a considerable "parallax" error. Parallax error is a visual error caused by viewing measurement markers at an incorrect angle.
- The outer face of the dial indicator can be moved so that the zero can be positioned over the pointer.
Part 2: Step-by-step instruction
- Select the correct gauge and attachment
Select the gauge type, size, attachment and bracket, which fit the part you’re measuring. Mount the dial indicator on a firm surface to keep it still.
- Ensure plunger is at 90 degrees
Adjust the indicator so that the plunger is at 90 degrees to the part you’re measuring.
- Press the plunger halfway in
Press the dial indicator gently against the part, and rotate the part –in this case a brake rotor-- one full turn. Keep pressing until the plunger settles about halfway into the indicator.
- Lock into position
Lock the indicator assembly into position.
- Rotate and read
Carefully rotate the brake rotor a couple of times, while you observe the dial readings face on.
- Record any movements
If the pointer hovers around a single graduation on the dial, the part has minimal run out, or surface distortion. If it moves significantly left and right, you should note these variations. Find the point of maximum movement to the left and move the dial so that zero is over this point. Continue to rotate the brake rotor. Find the point of maximum movement to the right, and note the reading. This will indicate the run out value. Continue this rotation several times to confirm the points of maximum variation.
- Check your results
Check your readings against the manufacturers specifications. If the deviation is greater than the specifications allow, consult your supervisor.
Using a feeler gauge
Part 1. Preparation and safety
Objective
- Show the correct choice and use of feeler gauge sets.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Never use feeler gauges on operating machinery.
- Feeler gauges are strips of hardened metal that have been ground or rolled to a precise thickness. They can be very thin and will cut through skin if not handled correctly.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- There are many types of feeler gauges, each with a specific application.
- Feeler gauges usually come in sets with a number of blades. The thickness of each blade is marked in thousandths of an inch and hundredths of a millimeter. A marking of 0.040 indicates the feeler is 40 thousandths of an inch thick. It may also indicate a measurement of 1.02 millimeters. A feeler marked 0.005 indicates the thickness is 5 thousandths of an inch. It may also indicate 0.12 millimeters.
- Some sets contain feelers made of brass. These are to take measurements between magnetic components.
- When measuring a spark plug gap, it is preferable to use wire feeler gauges. These feelers use accurately machined pieces of wire instead of metal strips.
- If the feeler gauge feels too loose when measuring a gap, select the next size larger and measure the gap again. Repeat this procedure until the feeler gauge fits snugly in the gap. If the feeler gauge is too tight, select a smaller size until the feeler gauge fits snugly in the gap.
Part 2: Step-by-step instruction
- Select correct type of gauge set
Select the appropriate type and size of feeler gauge set for the job you’re working on.
- Examine the wires or blades
Spread out the wires or blades and examine the markings on them. They indicate the size of the feeler. The measurements may be in inch or metric sizes – or both. They should also be clean, rust-free and undamaged, but slightly oiled for ease of movement.
- Measure gap
Select the part you wish to check, and make sure it’s clean. Choose one of the smaller wires or blades, and try to insert it in the gap on the part. If it slips in and out easily, choose the next size up. When you find one that touches both sides of the gap, and slides with only gentle pressure, then you’ve found the exact width of that gap.
- Keep gauges oiled
The oily film on the blade helps to minimize friction. So if you move the gauge and it feels tight, then you’ve got the wrong measurement.
- Check the specifications
Read the markings on the wire or blade, and check these against the manufacturer’s specifications for this component. If gap width is outside the tolerances specified, refer to your supervisor.
- Clean up and store
Finish the job by cleaning the feeler gauge set with an oily cloth to prevent rust when you put the set away.
Using a micrometer
Part 1. Preparation and safety
Objective
- Demonstrate the correct method of measuring using an outside micrometer.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Accurate measurement of components is one of the most important aspects of a technician's job. Inaccuracies lead to an incorrect diagnosis.
- Micrometers are available in metric and inch graduations. Common sizes range from 25-150 mm or 1-6 inches. Typically, an inch micrometer has an accuracy of 0.001" and a metric micrometer has an accuracy of 0.01mm.
- Some micrometers have an extra "vernier" scale that increases accuracy by a factor of 10 to 0.0001" or 0.001mm. Others will include a small dial gauge that serves the same function as the vernier scale. The dial is located on the micrometer frame where the locking lever is usually located.
- The size of the micrometer you will use is determined by its measuring range.
- It is important that other factors do not affect a micrometer measurement. For example, if a micrometer is held in your hand, the heat from your fingers can cause the frame to expand and give an inaccurate reading. Always hold the micrometer by the insulating block on the frame. This will prevent the heat from your fingers reaching the micrometer.
- It is important that the correct amount of force is applied to the spindle when taking a measurement. The spindle and anvil should just touch the component with a slight amount of drag when the micrometer is removed from the measured piece.
- Use the ratchet on the end of the thimble until you learn the correct feel for tightness.
- Always clean the micrometer and return it to its protective case when you have finished using it.
Component identification
- Some parts of this illustration are labeled. It is important to learn the names of these equipment components.
Part 2: Step-by-step instruction
- Handle with care
The outside micrometer is a delicate, precision, measuring instrument, and needs to be handled with care. Make sure the measuring faces are clean of any oil or particles. Use a clean piece of lint free cloth to wipe both faces; and also the item you’re going to measure.
- Hold the micrometer correctly
Inch micrometers give readings measured in units of “thousandth” of an Inch. Metric micrometers work on the same principles, with graduations of one-hundredth of a millimeter. To hold the micrometer correctly, use one hand to hold the frame by the plastic insulating block, and the other hand to hold the sleeve and thimble. Micrometers have a locking mechanism, to prevent movement in the spindle when you take it away from the item you’re measuring.
- Take a measurement
Undo the locking mechanism, and open the micrometer until it is wider than the object to be measured. Make sure that the micrometer is horizontal in relation to the object you’re measuring. Place the anvil against the object, then tighten the thimble gently until it has nearly touched the component. Then using the ratcheting thimble, tighten the micrometer until you feel the thimble clicking. Use the thimble lock to keep the reading constant, and gently withdraw the micrometer.
- Read the results
Examine the scale on the sleeve and the thimble. You will find the scale on the sleeve in units, either in parts of an inch or in millimeters. On the thimble you will find a scale in either a thousandth of an inch or a hundredth of a millimeter. Add the sleeve and thimble readings. This will give an accurate reading for the part you have just measured.
- Assess the information
Take readings at different points on the part to assess the amount of wear. Compare these readings to specifications. This will assist you in determining whether the part conforms to tolerances.
Using a tire pressure gauge
Part 1. Preparation and safety
Objective
- Use a tire pressure gauge and interpret the readings correctly.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Do not inflate tires above the pressure recommended by the tire manufacturer. If you do, the tire may explode or the wheel rim may give way and cause a blowout. The result will almost certainly be personal injury.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- There are two main types of tire pressure gauges — fixed workshop gauges and portable pocket size gauges.
- The two most popular types of pocket tire pressure gauges are the pencil type and the dial type.
- The pencil type looks similar to a pencil and contains a graduated sliding extension that is forced out of the sleeve by air pressure when it is attached to the tire valve.
- The dial type has a similar fitting to the pencil type but includes a graduated gauge and needle.
- Each gauge measures pressures in either pounds per square inch (PSI), kilopascals (kPa) or bar.
- One bar is equivalent to 100 kPa and 14.5 PSI.
- One PSI is equivalent to around 7 kPa. Some gauges have scales for both units of measurement.
- Pocket type tire pressure gauges are inexpensive and more accurate than the gauges provided by service stations. Service station gauges are often damaged by weather, misuse or being run over.
- There may also be a significant difference in readings between one service station tire pressure gauge and the gauge from another service station.
- If the same pocket type tire pressure gauge is always used to check tire pressures, then there will be no variation of readings.
- The tire pressure will vary from vehicle to vehicle, its use and driver preference. Recommended tire pressures are located on the vehicle manufacturer's tire decal. The recommended maximum tire pressure is located on the tire sidewall. Never inflate the tire above the recommended maximum pressure. The tire may explode, or the wheel rim may give way and cause a blowout.
Part 2: Step-by-step instruction
- Remove the valve cap
First, remove the valve cap from the tire valve. Be sure to place it where you can find it later!
- Fit pencil gauge to the valve
Make sure the graduated sleeve is seated into the gauge body, and then push the tire gauge chuck firmly onto the head of the valve. If air escapes, adjust the angle and your hand pressure until no more air leaks out.
- Read the scale
When the graduated sleeve slides out, remove the gauge from the valve without moving the sleeve and examine the scale.
- Add the numbers
Read the bottom number, then count the marks. Add them up, and you’ll find the tire pressure
- Examine dial gauge
When using a dial type gauge, check the graduations on the dial. They may be in pounds per square inch, or if it’s a metric gauge they will be in kilopascals or bar. Many gauges have all three graduations: PSI, kilopascals and bar. Once again, remove the valve cap and put it in a safe place.
- Attach the gauge to the valve
Attach the dial pressure gauge to the top of the valve. Adjust your hand pressure and angle, so that no air is escaping from the valve.
- Read the gauge
When the needle has jumped, remove the gauge from the valve, and read the dial. The numbers are by tens, and the marks between are units.
- Reset the gauge
Reset the dial gauge to zero by pressing the button on the neck of the dial. Repeat the procedure for all wheels. Remember to replace the valve cap on each wheel as you go.
- Check your results
Check your tire pressure readings against the specifications in the shop service manual. You will also find a tire decal listing the recommended tire size and pressures. This is usually located on the driver’s door, driver’s door pillar or glove compartment lid.
