Some interventions on the vehicle, such as engine repair, require the use of measuring devices. Measuring equipment is used to measure various physical quantities: length, thickness, weight, thrust force, pressure, temperature, angular displacement, flow, voltage, current, frequency, etc.
Measuring devices are precise and sensitive instruments. They should be treated with great care. You should never strike, throw or overload the measuring equipment as they may be damaged. The more precise they are, the more sensitive they are too rough handling.
Clean them after each use. Check and calibrate the measuring devices regularly. Before performing the measurement, find out about the expected exact values and permissible deviations. Even the slightest measurement error can be crucial to the correct operation of the engine and other systems on the vehicle.
Two systems of measures are used in the world, metric and imperial. Often measuring devices have a measuring scale of both systems. However, when we have the required values in one and the measuring device in the other system, then there is a problem when reading and comparing the measured value with the required one. The International System of Units has adopted a metric system where each unit is multiplied or divided by 10 to obtain larger or smaller units. This makes the metric system much easier to use, with less chance of error compared to the imperial system.
The basic unit of linear measurement in the metric system is the meter. The basic unit of linear measurement in the imperial system is the inch.
The automotive industry has largely accepted the metric system of measures, but technicians must know how to measure and work with both measuring systems. The following are some common equivalents in these two systems:
Length
1 m = 39,37 inch
1 inch = 2,54 cm
Weight
1 kg = 2,2046 pounds
1 pound = 453,59 g
1 ounca = 28,3495 g
Temperature
T(°F) = 9/5(T(°C) + 32°C)
T(°C) = 5/9(T(°F) – 32°F)
Pressure
1 bar = 14,504 psi
1 psi = 0,06895 bar
Torque
1 Nm = 0,7375 ft.-lb
1 ft.-lb = 1,3558 Nm
The technician is expected to perform various measurements during operation. So you need to know what tools are available and how they are used. Measuring tools can be classified according to the type of measurements they can make.
The simplest measuring tool, a ruler, is used to measure the length. In car workshops, measuring tape and machinist’s rules are used. Read more
Feeler gauges are measuring instruments for measuring the gaps, the interspace between two surfaces. They are delivered in sets of different sizes. Read more
Vernier caliper is a measuring instrument used for measuring outside, inside (bore) and depth measurements. Read more
The micrometer is a precise measuring instrument for measuring small distances. There are outside, inside, and depth micrometers. Read more
Dial indicators are most often used to measure the differences of rotating elements such as the camshaft, disc brakes, etc. Read more
A test light is used to check for voltage in an electrical circuit. There are two types of test lights, with a bulb and with an LED. Read more
The circuit tester probe is a multifunctional measuring and testing instrument for quick checking of the condition of the vehicle’s electrical networks. Read more
A multimeter is an electrical measuring instrument for measuring DC and AC voltage, current and resistance. Read more
Current clamps are used to measure the current on the electrical network of the vehicle without interrupting the circuit. Read more
The diagnostic tool is used to connect an external computer to the ECU (electronic control units) on the vehicle. Read more
An automotive oscilloscope (lab scope) is a digital measuring device specialized for measurements on the vehicle. Read more
See also
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