Dictionary of technical terms (Chevrolet Trailblazer 1)

A

• Automatic switch: a device for protecting an electrical circuit from overload by opening the circuit when the current exceeds a certain limit value. Some circuit breakers are manually reset after they trip, but most are reset automatically.
• Ampere: the magnitude of the electric current produced when a voltage of one volt is applied to a circuit having a resistance of one ohm.
• Ammeter: a device designed to measure the current in amperes in a circuit. Ammeters are connected in series to the circuit being tested.
• Analog computer: a microprocessor that receives analog electrical impulses as input.
• Hydrometer: a device for measuring the concentration of a solution.
• Atmospheric pressure: the pressure on the earth's surface created by the atmosphere. At sea level, atmospheric pressure is 101 kPa at 0°C.

B

• Bakelite: a heat-resistant plastic-based insulating material commonly used in printed circuit boards and transistor components.
• Ballast resistor: a resistor in the primary ignition circuit that serves to reduce the voltage after the engine has started, thus preventing increased wear of the ignition system components.
• Drum brake: a brake assembly consisting of two brake shoes and one or two working brake cylinders mounted on a fixed support plate. The unit is mounted inside the brake drum, which rotates with the wheel hub.
• Bearing raceway: the rolling surface of balls, rollers or needles on the inner or outer race of a bearing.
• Bimetallic temperature sensor: a sensor or switch consisting of two plates of dissimilar metals that are placed close to each other. When heated or cooled, the plates bend to one side, since their materials have different degrees of thermal expansion. These types of sensors are typically used as circuit breakers.
• Control unit: an electronic device that controls the low voltage supply circuit to the ignition coil electrodes. When the primary low voltage circuit is opened, an ignition pulse is sent to the coil electrodes.
• Cylinder block: the main body part of the engine, in which the cylinder holes are bored. The crankshaft and other main engine parts are installed in the block.
• Electronic ignition system: a system in which the distribution of ignition timing between cylinders is controlled by an electronic control unit, commonly referred to as the engine control unit. The design of such systems does not provide for the presence of a circuit breaker-distributor.
• Engine Control System (ECS): ignition system unit (booster or igniter). See Control Unit.

IN

• Vacuum regulator: a device that shifts the ignition timing in accordance with the increase in vacuum in the engine.
• Vacuum gauge:a measuring device designed to measure the degree of vacuum in a chamber.
• Top Meter Point (TMP): the point of travel at which the piston reaches its top position on the compression stroke.
• Air damper: a device, usually a movable valve, located in the intake manifold to vary the rate of air flow.
• Voltmeter: a device designed to measure voltage in volts. Voltmeters are always connected in series with the circuit being tested.
• Intake manifold: a cast part that is a system of channels or tubes designed to admit air or a fuel-air mixture into the cylinders.
• Secondary circuit: the high voltage circuit of the ignition system, typically over 20,000 volts. The secondary circuit includes the ignition coil and its wires, the distributor cap and rotor, and the spark plugs and their wiring.
• Insert: component of a bearing (usually removable); anti-friction bearings are used as plain bearings.
• Input shaft: the shaft to which the torque is applied. Typically, the shaft drives a gear or cogwheels.
• Exhaust manifold: cast tubes or channels through which exhaust gas is discharged from the engine.
• Output shaft: a shaft that transmits torque from a unit, such as a gearbox.
• Viscosity: the ratio that determines the fluidity of a liquid.

G

• Generator: a device that converts mechanical energy into electrical energy.
• Torque converter: a turbine designed to transmit kinetic energy from a driving part to a driven part by means of a hydraulic effect, which ensures a change in gear ratio and torque. In automobiles, the torque converter transmits torque from the drive disk to the automatic transmission shaft.
• Master cylinder: a device for the primary compression of fluid in a hydraulic system. In a car, master cylinders are found in the brake system and in the hydraulic clutch system. The clutch master cylinder is driven directly by the pedal, and the brake cylinder is driven by the vacuum booster rod.
• Cylinder head: a removable part of the engine that is usually attached to the cylinder block from above. The cylinder head contains all or most of the combustion chambers. The cylinder head of an overhead valve engine contains the valves and valve mechanism components. The overhead camshaft is also installed in the cylinder head.

D

• Sensor:a device designed to determine the operating parameters of an engine, as well as to measure the pressure and temperature of the environment. Typically, sensors are an electronic device that transmits pulses to the control unit. Some sensors function as regular switches, as well as potentiometers, supplying pulses of different voltage depending on changes in the measured parameters or conditions.
• Internal combustion engine: a unit in which thermal energy is converted into mechanical energy.
• Detonation:an unwanted explosion of the air-fuel mixture in the combustion chamber due to overheating or excessive compression, as well as early ignition or excessive leanness of the mixture.
• Diaphragm:a thin flexible wall between two cavities, such as in a vacuum regulator.
• Diode: an electrical device that conducts current in only one direction.
• Disc brake: a hydraulic brake unit consisting of a brake disc mounted on an axle and a caliper, which usually contains two brake pads. The pads are driven by hydraulic pressure, causing them to be pressed against the disc from both sides. At the same time, the rotation speed of the disk decreases due to the action of frictional force.
• Differential: an assembly consisting of a system of gear wheels. The purpose of the differential is to ensure that the drive wheels rotate at different speeds, if necessary.

3

• Gap: the space between parts, such as a shaft and a hole.
• Shut-off valve: a valve designed to allow air or fuel to pass through, or to distribute a vacuum, in one direction only.
• Crown gear: a ring gear attached to the differential housing, mounted on the flywheel, or included as a component of a planetary gear system.

AND

• Measuring unit: a mechanical, electrical, hydraulic, or electromagnetic device that serves to transmit sensor input signals.
• Needle bearing: a bearing in which there are several (usually a lot) long and thin rotating rollers.
• Induction:a method of distributing electrical energy in the form of a magnetic field. Typically, this is the principle by which an ignition coil operates, producing the voltage needed to fire a spark from a spark plug.

TO

• Caloric ignition: continued engine operation after the ignition is turned off.
• Calorie number: a conventional value proportional to the average indicator pressure at which, during spark plug testing on a motor calibration rig, glow ignition begins to occur in the cylinder, i.e. ignition (before a spark) of the working mixture from an external source - overheated parts of the spark plug or piston. The higher the heat rating, the higher the heat output of the spark plug.
• Carburetor: a device, usually installed on the intake manifold, in which air is mixed with fuel in the proportion necessary for complete combustion.
• Carter: the lower part of the engine in which the crankshaft and connecting rod and piston group are installed.
• Catalytic converter: a device in the exhaust system that converts toxic combustion products into carbon dioxide and water vapor through a catalytic thermal reaction.
• Coil (ignition): an electrical transformer that supplies voltage to the spark plugs.
• Oxygen sensor: a device that registers the amount of oxygen in the exhaust gases and transmits pulses to the control unit. After processing the pulses received from the sensor in the control unit, the appropriate fuel-air mixture ratio is set.
• Valve: a device for regulating the pressure, flow rate, and consumption of liquid or gas.
• Valve clearance: the measured clearance in the valve mechanism between the valve stem and the rocker arm or the camshaft cam and tappet.
• Overhead valve mechanism: in this mechanism, the camshaft is located in the cylinder block, and the valves are in the cylinder head. The camshaft actuates the valves using cam lobes and tappets.
• Crankshaft: the main drive shaft of the engine, which converts the reciprocating motion of the pistons into the rotary motion of the flywheel.
• Collector: a cast part that is a system of channels or tubes designed to connect the engine cylinders to the intake or exhaust tract.
• Combination valve: a device used in some fuel systems that is designed to divert fuel vapors to an adsorber. When the fuel level drops, the valve also serves to release pressure from the fuel tank and allow fresh air to enter, thereby preventing the formation of vapor locks.
• Combined manifold: a unit that is both an intake and exhaust manifold.
• Capacitor:1. An electrical device designed to store electrical charge to prevent voltage surges. 2. A device in an air conditioning system, structurally similar to a radiator, in which the refrigerant changes from a vaporous to a liquid state, releasing heat.
• Capacitor: a device for accumulating an electric charge.
• Excess air coefficient: the ratio of the actual mass of air supplied for combustion of 1 kg of fuel to the theoretically required mass.
• Torque: rotational force applied to an object.

M

• Flywheel: a disc-shaped part bolted to the rear end of the crankshaft. A toothed ring is installed on the flywheel. When the engine starts, the starter gear is engaged with the ring gear by the solenoid valve, transmitting the starting torque to the flywheel.
• Dead center: the extreme upper or lower point of the piston stroke.

N

• Air injection: one of the ways to reduce the amount of harmful emissions into the atmosphere, which consists of forcing air into the engine exhaust tract. Fresh air entering the hot exhaust manifold helps to burn off unburned fuel, thereby preventing its release from the exhaust pipe.
• Setup: a regular maintenance procedure that usually involves replacing and adjusting components of the engine's electrical and fuel systems to ensure optimum engine performance.
• Newton meter: the torque created when 1 kgf is applied to a 1 m long lever arm.

ABOUT

• Backfire: abnormal combustion of gases in the intake or exhaust system, resulting in a loud explosion.
• Nitrogen oxides (NO): chemical compounds of nitrogen that are a by-product of combustion. When nitrogen-containing impurities mix with carbon, soot is formed.
• Ohm: (Ohm) is a unit of measurement of the electrical resistance of a conductor. 1 Ohm is the resistance that occurs when the current is 1 A and the voltage is 1 V.
• Ohmmeter: a device designed to measure resistance in an electrical circuit in ohms.
• Axial clearance: clearance in a direction parallel to the longitudinal axis of the shaft or bearing.
• Axial displacement: measured shaft axial clearance.

P

• Primary chain: an electrical circuit in the ignition system in which low voltage is generated. This circuit includes devices such as the ignition switch, ballast resistor or high resistance winding, shunt, ignition coil, control unit and inductive sensor, as well as the associated wiring and connectors.
• Gear ratio: the ratio of the number of teeth on a gear and the engagement gear.
• Transfusion: accumulation of excessive amounts of fuel in the intake manifold and combustion chamber, which prevents ignition of the fuel-air mixture. As a result of the spill, the engine does not start.
• Fuse box: a device for protecting an electrical circuit from overload by opening the circuit when the current exceeds a certain limit value. The principle of operation of the fuse is to burn out the wiring, designed to transmit a certain current, when an overload occurs in the circuit. When the fuse wiring burns out, the circuit is broken.
• Overdrive: torque transmission in which the crankshaft speed increases and the torque decreases.
• Bearing: a support part in a sliding shaft-hole fit, designed to reduce friction.
• Piston ring: a split ring installed in a piston groove to create a seal between the piston and the cylinder bore. Most pistons have three rings: two compression rings and one oil scraper ring
• Firing order: the order of ignition in the engine cylinders, as well as the order in which the breaker closes the distributor contacts.
• Preload: a specified load applied to a bearing during assembly or adjustment.
• Converter: a device designed to convert the magnitude of a load into an electrical impulse.
• Press fit: an interference fit in which the shaft diameter is larger than the bore diameter.
• Conductor: a material through which an electric current can flow.
• Intermediate shaft: a shaft driven by the main shaft and, in turn, transmitting rotation to other parts.
• Gas breakthrough: a breakthrough through the piston rings into the engine crankcase of combustion products consisting of water vapor and unburned fuel. Crankcase gases are discharged through the ventilation system, which prevents the accumulation of aggressive acids in the crankcase.
• Back pressure: resistance in the exhaust system that slows the flow of exhaust gases from the combustion chambers.

R

• Working brake cylinder: a hydraulic device located in a drum brake. The working cylinder serves to drive the brake shoes of the drum brake.
• Clutch slave cylinder: a device that serves to disengage the clutch by applying hydraulic force.
• Vacuum in the manifold: vacuum in the engine intake manifold, formed immediately behind the throttle body. The highest degree of vacuum in the manifold is created in idle mode. As the crankshaft speed increases, the degree of vacuum decreases.
• Distributor: a mechanically driven device mounted on an engine that serves to distribute the spark supply to the cylinders depending on the position of the pistons.
• Camshaft: the camshaft of the engine that drives the valve mechanism. The camshaft is driven by the crankshaft via a toothed belt, chain or gear transmission with a gear ratio of 1/2.
• Overhead camshaft (OHC): camshaft mounted on top of the cylinder head. The valves are driven either directly from the camshaft cams or via rocker arms.
• Spray: transformation of liquid into a suspended dense fog.
• Adjusting shim: a spacer of a specified width installed between parts to ensure proper performance.
• Regulator: a device that serves to maintain current and/or voltage in a circuit at a certain level.
• Resistor: an electrical device, usually having a winding, that is used to change the resistance in a circuit.
• Relay: a switch that automatically opens and/or closes a circuit.
• Roller bearing: a bearing with a reinforced inner and outer race, between which are located rotating rollers made of hardened steel.
• Rotor: 1. A disc-shaped part of a disc brake that supports the brake pads; also called a brake disc. 2. A part installed on the distributor shaft that alternately closes the contacts of its cover.

WITH

• Spark plug: a device that is screwed into the combustion chamber of a spark-ignition engine. The spark plug design consists of a conductor surrounded by a ceramic insulator, which is located inside a conductive housing. The electrical charge from the spark plug wire passes through the conductive core and forms an arc in the air space to the negative electrode, which is the tip of the conductive body. As a result, the spark ignites the fuel-air mixture in the combustion chamber.
• Air-fuel ratio: the ratio of the mass of air and gasoline in the mixture entering the combustion chambers.
• Resistance: opposition to the flow of current through a circuit or electrical device, measured in ohms. Resistance is equal to the ratio of voltage to current in a circuit.
• Compression ratio: the ratio of the total volume of the cylinder to the volume of the compression chamber.
• Hub: the central part of a wheel or gear.
• Support: a hydraulic device in a disc brake system that covers the brake disc (rotor) on both sides. The caliper has at least one piston and two brake pads. The pads are pressed against the disc by the hydraulic force of the piston.

T

• Tachometer: a device for measuring, usually in revolutions per minute, the rotational speed of a motor shaft, gear, etc.
• Thermostat: a device in the engine cooling system with a valve that is closed when cold and gradually opens as the engine warms up, controlling the temperature and circulation of the coolant.
• Brake shoe:a component of the brake system that consists of a friction lining riveted or glued to a metal plate. The pads are pressed against the working surface of the brake disc or drum, resulting in a slowdown in the vehicle's speed.
• Brake lining: brake shoe lining made of friction material. The term is commonly used to describe the measurement of the allowable thickness of linings.
• Transistor: a semiconductor element that is driven by a low voltage circuit and performs a switching function.
• Turbocharger: turbine compressor driven by exhaust gas pressure on the rotor blades. The turbocharger sucks in air and forces it into the combustion chambers at a pressure higher than atmospheric. Increasing the amount of air allows more fuel to be supplied to the chambers, resulting in increased engine power

U

• Carbon monoxide (CO): a colorless, odorless gas released as a by-product of combustion. Carbon monoxide is extremely poisonous and dangerous in confined spaces. Slowly accumulating to toxic concentrations in the blood, it can cause fatal poisoning.
• Hydrocarbon (CH): a chemical substance whose crystal lattice contains atoms of hydrogen and carbon. The main pollutant emitted from combustion chambers as a by-product of combustion.
• Ignition angle: the angle of rotation of the shaft at which one ignition cycle occurs.
• Mounting pin: a pin that fixes the initial relative position of mating parts.

F

• Nozzle: a fuel system device that serves to inject fuel into the combustion chamber under a certain high pressure and at a set frequency. Fuel is transported to the injector under low pressure.

C

• Trunnion: the surface of a bearing that is mated with the surface of a shaft.
• Centrifugal ignition timing adjustment: a mechanical method of adjusting the ignition angle, which consists of moving the centrifugal weights of the distributor apart depending on the shaft rotation speed.
• Chain: a continuous circuit through which an electric current flows. In some cases, the term is used to describe the direction of fuel.
• Cylinder: a cylindrical bore in a block in which the piston is installed.

Sh

• Ball bearing: a bearing with a reinforced inner and outer race, between which are located rotating balls made of hardened steel.
• Gear: the smaller of two meshing gears
• Splines: grooves made during machining or casting on the mating surfaces of a shaft and a hole. This fit does not allow the parts to move relative to each other in the plane of the cross-section, while at the same time providing the possibility of mutual movement of the parts in the direction of the shaft axis.
• Key: a small fastener that is installed in the grooves of the shaft and hub to prevent the parts from shifting in the plane of the cross-section.

SCH

• Probe: typically a metal plate of a precisely defined thickness used to measure the gap between parts.

E

• Solenoid valve: a device with an inductive winding in which magnetic induction is converted into mechanical work.
• Electrical conductivity: the ability of materials to conduct electric current. Determined using an ohmmeter.

I

• Anchor: a soft metal core coated with epoxy resin and wound with a winding. It is used to convert electrical energy into mechanical energy, for example, in an electric motor or relay, as well as electrical energy into mechanical energy, for example, when rotating in the magnetic field of a generator.

[The article is reprinted from the website: «ChevyMan»]