Engine Components and Timing Systems: Maintenance and Repair

Posted on Dec 11, 2024 in Technology

ITEM 9: Engine Components

Flywheel

The flywheel is the part that stores kinetic energy of the working careers or dies and gives non-motor racing. It is also responsible for regulating the operation of motor rotation.

  • Its size depends on the number of cylinders, and the greater the number of cylinders, the lower the irregularity of rotation.

Process control:

  • Reduces engine vibrations.
  • A certain number of revolutions in the car shake when you release the clutch: incorrect link starter pinion to the crown.
  • To engage the starter gear to the crankshaft, the crown is not moving.

Crankshaft

It is a tree engine crankshaft which houses many elbows as has the engine cylinders and which receives the force of combustion.

  • The crankshaft with the crank generates crank-crank motion that transforms the linear motion reciprocating piston rotating the flywheel.

Shaft Balance

  • Static Balance: It is done in the design process of engine components, trying to divide the whole mass of the relationship of the crankshaft, this is always in repose.

  • Dynamic Balance: It is achieved when the resultant of the moments generated by the centrifugal forces, taken with respect to any point on the axis, becomes zero. It normally takes one of the supports as a reference.

Crankshaft Process Control:

  • Excessive motor roughness.
  • Lack of engine performance.
  • Abnormal vibration motor to a certain number of revolutions.
  • The crankshaft does not move to engage the starter motor with the flywheel ring gear.
  • Scarce oil pressure.

Connecting Rod

The connecting rod is the engine component that transmits the force of the piston to the crankshaft, transforming the linear motion reciprocating piston rotary output for its coupling with the crankshaft.

  • The rod is made of tempered alloy steel with a copper sleeve inserted into the bolt coupling with the piston.

Checks on the Connecting Rods:

  • Alignment of the rods.
  • Control the diameter of the connecting rod cap.
  • Control inside diameter of the big end.
  • Weight control rods.

Connecting Rod and Crankshaft Caps

Elements are placed between the rod and the crankpin and between the crankshaft and block. Its mission is to reduce friction between the workpiece and thus control the temperature and the wear of them.

  • Corrosion: It consists in the gradual destruction of metallic bodies. In the case of caps, it is visible by the formation of dark areas and small holes or pits.

  • Heating: Overheating of the bearings can cause the friction layer to be removed, leaving the steel unprotected.

  • Galling: The lack of oil in the caps leads to your work surface this wear becoming brighter. If there is a complete lack of lubrication, drag material through the center thereof in contact with the sliding surface bearing supported crankshaft or crankpin.

Crank-Piston Assembly

The union of the piston rod is made by means of a pin called bolts that allow the play necessary between the two to carry out part of the mission of the connecting rod-crank assembly and also supports the same forces that the plunger.

Mount Properties:

  • Fixed to the piston: The piston is attached to the carriage bolt through a fastener such as a pin, bolt, screw, etc., which is fixed at the same.

  • Fixed to the rod: No cap usually be attached for lodging, as no relative movement to and between the nut and the connecting rod.

  • Float: It is widely used in addition to being easy to mount, more evenly distributes loads due to friction between the two.

Pistons

The mission to be carried out this element is: get the force of expanding gases, pushing down his career. This in turn, through the bolt, transmits motion to the rod and the crankshaft.

Types of Pistons as to Your Work:

  • Cast Pistons: The head of the piston, the area segments, and bolt.

  • Forged Pistons: These are mainly piston engine series of high loads and racing engines.

  • Slots Pistons Rings and Piston Pin Bushings: These pistons for diesel engines.

  • Pistons Cooled Slotted Segments: In the case of these pistons is combined carrier segments and the cooling channel.

  • Pistons Slotted Segment, Channel Cooling and Extra Protection to the Head: Used in diesel engines.

  • Pistons Slots and Cooling Channel Segments: Used where operating temperatures prevail particularly high.

Types of Pistons as to its Construction Method:

  • Flathead piston lateral cavities for the valves.
  • Concave piston head lowered.

Piston Impairments:

  • Drilling the piston head.
  • Stuck and dragged segments.
  • Clogged, worn segments.
  • Cracks in the piston crown.

Segments

The segments or snap rings located in grooves in the exterior of the pistons, fulfill the following missions:

  • Seal the cylinder and piston.
  • Supply some heat to the cylinder walls.
  • Do not grease the sides of the cylinder, the oil collecting corresponding segment.

Types of Segments:

  • Compression or fire segments.
  • Scrapers or compression segments.
  • Lubrication segment.

Verification of Segments:

  • Oil Consumption:

    • Too much clearance between the piston and cylinder.
    • A bad coupling between the segments and the piston.
    • Poor nutrition between the piston and rod.

  • High Attributable Humor:

    • An excessive clearance between piston and cylinder or between the piston and its respective crank.
    • A crank-piston misalignment.
    • Interference between piston and piston pin. The latter occurs in floating mounts.

ITEM 10: Distribution System

1. Distribution System: Is in charge of synchronizing the opening and closing valves with the piston moves. It gets the intake and exhaust valves to begin to open and close when the piston is at a certain point, to get the opening and closing the valves need a series of intermediate elements to transform circular motion into a movement of the crankshaft alternative longitudinal valves.

Transmission Ratio: Is a number that indicates how many turns a pinion turns over another that conveys movement.

OHV Distribution: OHV distribution systems have the camshaft mounted in the block and the movement is transmitted to the valve from the cam through a tank in a pusher or a pushrod and a rocker arm that rotates about the respective axis.

OHC Distribution: The camshaft distribution systems OHC is located at the top of the stock, which are necessary unless intermediates and thus there is less inertia forces and can reach higher revolutions.

DOHC Distribution: Multi-valve used in distributions where the intake valves are located on one side and the exhaust valves on the other, having a camshaft for each type of valve.

2. Control System of Distribution: The movement of driven gear is always transmitted with a gear ratio 2 / 1. This pinion located on the camshaft should have twice the teeth located in the crankshaft as its angular velocity will be half. Types of controls: Transmission through sprockets, chain, and timing belt.

Transmission by Gears: Mainly used when the camshaft is located in the block. Sometimes he uses an intermediate pinion gear ratio maintaining, changing the direction of rotation of the driven gear.

Transmission by Chain: This system is most used when the camshaft is located in the block, but is also used when the camshaft is located in the butt, with the passage of time that causes stem wear slacks and these are result in noise. To alleviate this problem has one or more tensioners that maintain a constant operating voltage.

Toothed Belt Drive: Minimizing the noise and wear are lower. It is used especially when the camshaft is located in the head.

3. Distribution Components: Components: camshaft, valves, taques push rods, rocker arms, springs.

Camshaft: Is the body that controls the timing of opening and closing valves. This consists of an axis of forged carbon steel and cement which are machined cams for opening and closing intake and exhaust valves.

There are different profiles for cams, depending on whether:

  • The valve is exhaust or intake.
  • The engine is diesel or gasoline.
  • The number of revolutions is the normal operating range.

Forms of the Cams:

  • Oval Profile: With this type of profile opening and closing of the valve occurs in a slow.

  • Shear Profile: This type of profile is achieved valve opening and closing fast.

Valves: Components in the combustion chamber is responsible for opening and closing the inlet and outlet gases of each cycle of operation. Valve parts: head, stem, tail. During engine operation the intake valve can vary its temperature to 400 ºC and exhaust up to 800 ºC. At 5000 rpm rotation of the crankshaft, valves seat beat 2500 times per minute.

Dimensions of the Valves:

  • Diameter of Head: When this is higher, the better the filling to higher speed, because if the rpm is higher there is less time to introduce the flow for each cycle.

  • Height: Length valve moves longitudinally.

  • Section: Passing gas is a function of the valve diameter and length.

  • Seat Angle: Formed by generating cone seat valve head.

Cooling of Valves:

The inlet valve is cooled by the fresh gas entering the engine, the exhaust valve dissipates the heat when in contact with the seat.

Valve Seats: False pieces are placed on the head and pressure, make support of the valve head to achieve a watertight seal.

Valve Guides: False pieces placed pressure on the head, used as valve stem in its displacement, prevent premature wear of the stock and heat away from the valve.

Tanks:

  • When the camshaft is located in the cam block to the pushrod.
  • If the camshaft is located in the butt from the rocker cam to the valve.

Hydraulic Tanks: To avoid making the typical rock-breaking setting or set of valves and to minimize noise caused by the same classic, used hydraulic tappets which are adopted at all times to the expansion of the different elements.

When there is more than the allowable slack, the spring located between the plunger and taque expands. The pressurized oil fills the existing volume below the plunger and the body produces a small leak that allows you to remove excess oil, when the components of the distribution swell on an increase in temperature, it produces an oil leak in varying tank in the slack automatically.

Push Rods: They are used in distribution systems OHV, its mission is to transmit the movement from the pusher or taque to swing.

Rocker: Are the levers that directly or indirectly transmit the movement of the cam to the valve. Types:

  • Swivel Rocker: Used in motors using push rods at one end receives the impulse and transmits it on the other, tilting in the central part.

  • Oscillating Rocker: Used in engines with overhead cam head, the movement is directly receives the balance beam in its central zone, swinging at one end and transmitting the movement in the other.

Valve Springs: These are responsible for maintaining the valve is always closed.

The aim of this type of construction is to avoid bouncing own dock and therefore the valve due to continual reciprocating motion.

ITEM 11: Distribution Systems

Verification and Control in Distribution Systems:

  • Lack of seal on the valves.

  • Shift in the timing mechanism of the distribution of the rise and fall of the pistons and the valve opening.

  • Noise distribution is produced by one or more elements of the distribution due to its poor condition or adjustment.

  • Fatigue and wear of the elements of the distribution.

Maintenance of Distribution Systems:

  • Substitution-mileage, service intervals ranging from 40,000 km at 3 years in older engines, the 160,000 or nine in the latest engines.

  • The tensioner and rollers must also always be replaced.

Precautions Straps

The Depth of Distribution:

  • By brand.

  • For holes.

  • It stops at the moving parts and hole.

  • To immerse, crankshafts, camshafts, and fuel injection pumps.

Valve-Adjustment

  • Automatically through hydraulic tappets.

  • By adjusting screw.

  • Through pills calibrated.

The methods for: tread and outlet valve crossing method.