API base stock oil groups

Group oil type

I fractionally distilled petroleum followed by solvent extraction

II Fractionally distilled petroleum followed by hydro cracking

III Group II oils further hydrocracker to produce higher viscosity index values

IV Base stock oil of polyalphaolefins (AOs)

V Polyolesters / polyalkylene glycols (PAGs)/others

Cracking: Heating of higher molecular weight petroleum fractions in the presence of a catalyst to give a lower molecular weight fraction.

Dew axing process: Lubrication feed stocks typically have an increased wax content from other processing and refining (de-asphalting). These waxes can be removed catalytically or by solvent dew axing. A reactor contains a dew axing catalyst followed by a second reactor with a hydrogen finishing catalyst to saturate olefins from the dew axing reaction.

Fractional distillation: Separation of a mixture of components or fractions by their boiling points by heating them to that point. This is a continuous process in the petroleum industry and the most common separation technique used in refineries.

Hydro treating: Generally, the first process before cracking. Petroleum fractions are reacted with hydrogen at 400°C with a cobalt oxide/molybdenum oxide catalyst . This decreases the amount of nitrogen and sulfur compounds and prevents poisoning.

Kinematic viscosity: Viscosity is a fluid’s internal resistance to flow, or its thickness. Kinematic viscosity is a measure of the ratio of the viscous force to the inertial force of the fluid or v = µ/ρ,

where µ is the dynamic viscosity (in centipoises [cP]), ρ is the density (in grams per cubic centimeter), and v is the kinematic viscosity (in centistokes [cSt]).

Reforming: Catalytic reforming is the process of increasing the number of double bonds on a petroleum product but maintaining the same number of carbon atoms. This process is done at high temperatures in the presence of a platinum or rhenium catalyst on alumina.

Solvent extraction: Solvent extraction is a method of separating compounds based on their solubility in different immiscible liquids. In industrial processes, solvents are typically transferred from an aqueous phase to an organic phase.

Viscosity index: Viscosity index is a measure of the change of kinematic viscosity with temperature and indicates an oil’s ability to lubricate with a change in temperature.

The VI scale set by the Society of Automotive Engineers (SAE) is 0 (worst) to 100 (best). VI = 0 is naphthenic oil and VI = 100 is paraffinic oil.

Engine oil Function

Chemists play a role in the addition of additives to improve the properties of motor oil. As steel and aluminum parts move closely against one another, friction between the two parts creates heat and wears away the metallic surfaces. This will lead to decreased efficiency, increased fuel consumption, decreased power output, and eventually engine failure. Engine additives are devised to combat these consequences. A list of engine additives follows; however, rather than discussing each one in depth, we will discuss only some of the more important ones:

Extreme pressure additives

Detergent additives

Metal deactivators

Corrosion inhibitors

Antifoam agents

Friction modifiers

Viscosity index improvers

Antioxidants anti wear additives; and• emulsifying agents

Motor oil will create a film between the moving metallic parts, thereby lessening the contact between them, decreasing the amount of friction and wear, and removing heat. Toward the top of the piston around the compression rings, temperatures can reach up to 160°C, while in diesel engines the temperatures can raise by another 150°C. Secondary heat exchangers called engine oil coolers (EOCs) are a design feature added to minimize these effects. They are basically plate coolers made of four or five thin plates located on an external loop in the airflow of the vehicle.

Another function of the motor oil is to coat the parts to minimize exposure to oxygen. Corrosion inhibitors within the oil assist in this function. Sludge buildup is a result of degradation of the oil after exposure to the heat and extreme pressure conditions of the engine. Many motor oils have detergents and dispersants to combat this problem. However, microscopic particles will invariably be produced from wear and cause erosion. The oil filter is another design feature that will help with the overall process. Engine oil lubricates rotating parts in the crankcase of a vehicle as it is applied to crankshaft journals, rods, and bearings. During testing and design of oil coolers, thermocouples are placed at the engine sump at the bottom of the crank to measure temperature of the oil. In many engines, tabulators are placed in the oil pan to spread the oil on the reciprocating members of the engine. The oil pump will send oil through the filter into the galleries and across critical parts such as the camshaft bearings. Oil from holes in the main journals will move through passageways inside the crankshaft to exit holes in the rod journals to lubricate the rod bearings and connecting rods. Passageways through the rods carry oil from the rod bearings to the rod–piston connections and lubricate the contacting surfaces between the piston rings. Interior surfaces of the cylinders are lubricated from oil coming from the rod bearings. There it will be a barrier between the piston rings and cylinder walls before oil returns to the sump.

Engine oil grades

Engine oil is graded based on an SAE coding system based on kinematic viscosity. The grades range from 0 to 60 in increments of 10. An oil grade with a “W” behind it designates a winter or cold-start grade; this means that the oil will have a better flow viscosity at lower temperatures. For single-grade oils, viscosity is measured at 100°C and the range that the viscosity falls in is called its weight. Single-grade oil’s viscosity will increase on a logarithmic scale as the temperature increases. Specific motor oil will have a high viscosity when cold and a lower viscosity when hot. The viscosity difference in single-grade oils will be too large to provide adequate protection for today’s vehicles. Viscosity improvers such as poly butane are added to decrease the difference between the two extremes. It is these additives that designate a multi grade oil, which will have the viscosity of the base number when cold and the viscosity of the second number when hot. Multi grade oils have two grade designations. For instance, the “30” in the 5W30 grade means that the viscosity of this oil at 100°C corresponds to the viscosity of a single-grade 30 oil at the same temperature. The first number, “5,” is associated with the winter measurement and is not rated at a single temperature. A multi grade with a first number of 5 can be utilized as well as a single-grade 5. SAE procedures test a 5W oil at –30°C; a 0W oil is tested at –35°C and a 10W oil is tested at –25°C on a cold crank simulator.

While Camber, Caster & Toe-in are the settings that are always checked when doing a wheel alignment, they are not the only settings. Below is a list of the alignment settings that are important for a wheel alignment technician to know about in order to diagnose front end problems.
To find out more about each of these measurements, click on them.

• Camber
• Caster
• Toe
• Steering Axis Inclination (SAI)
• Included Angle
• Scrub Radius
• Riding Height
• Set Back
• Thrust Angle
• Steering Center
• Toe Out on Turns

Camber

When camber specifications are determined during the design stage, a number of factors are taken into account. The engineers account for the fact that wheel alignment specifications used by alignment technicians are for a vehicle that is not moving. On many vehicles, camber changes with different road speeds. This is because aerodynamic forces cause a change in riding height from the height of a vehicle at rest. Because of this, riding height should be checked and problems corrected before setting camber. Camber specs are set so that when a vehicle is at highway speed, the camber is at the optimal setting for minimum tire wear.
For many years the trend has been to set the camber from zero to slightly positive to offset vehicle loading, however the current trend is to slightly negative settings to increase vehicle stability and improve handling.

Caster

Positive caster improves straight line tracking because the caster line (the line drawn through the steering pivot when viewed from the side) intersects the ground ahead of the contact patch of the tire. Just like a shopping cart caster, the wheel is forced behind the pivot allowing the vehicle to track in a straight line.
If this is the case, then why did most cars have negative caster specs prior to 1975 ? There are a couple of reasons for this. In those days, people were looking for cars that steered as light as a feather, and cars back then were not equipped with radial tires. Non-radial tires had a tendency to distort at highway speed so that the contact patch moved back past the centerline of the tire (Picture a cartoon car speeding along, the tires are generally drawn as egg-shaped). The contact patch generally moves behind the caster line causing, in effect, a positive caster. This is why, when you put radial tires on this type of car, the car wanders from side to side and no longer tracks straight. To correct this condition, re-adjust the caster to positive and the car should steer like a new car.

Toe

Like camber, toe will change depending on vehicle speed. As aerodynamic forces change the riding height, the toe setting may change due to the geometry of the steering linkage in relation to the geometry of the suspension. Because of this, specifications are determined for a vehicle that is not moving based on the toe being at zero when the vehicle is at highway speed. In the early days prior to radial tires, extra toe-in was added to compensate for tire drag at highway speed.
On some older alignment machines, toe-in was measured at each wheel by referencing the opposite wheel. This method caused problems with getting the steering wheel straight the first time and necessitated corrective adjustments before the wheel was straight. Newer machines reference the vehicle’s centerline by putting instruments on all four wheels. For more information on this see Steering Center and Thrust angle

Steering Axis Inclination (SAI)

SAI is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. This angle, when added to the camber to form the included angle (see below) causes the vehicle to lift slightly when you turn the wheel away from a straight ahead position. This action uses the weight of the vehicle to cause the steering wheel to return to the center when you let go of it after making a turn. Because of this, if the SAI is different from side to side, it will cause a pull at very slow speeds. Most alignment machines have a way to measure SAI; however it is not separately adjustable. The most likely cause for SAI being out is bent parts which must be replaced to correct the condition. SAI is also referred to as KPI (King Pin Inclination) on trucks and old cars with king pins instead of ball joints.

Included Angle

Included angle is the angle formed between the SAI and the camber. Included angle is not directly measurable. To determine the included angle, you add the SAI to the camber. If the camber is negative, then the included angle will be less than the SAI, if the camber is positive, it will be greater. The included angle must be the same from side to side even if the camber is different. If it is not the same, then something is bent, most likely the steering knuckle.

Scrub Radius

Scrub radius is the distance between where the SAI intersects the ground and the center of the tire. This distance must be exactly the same from side to side or the vehicle will pull strongly at all speeds. While included angle problems will affect the scrub radius, it is not the only thing that will affect it. Different wheels or tires from side to side will cause differences in scrub radius as well as a tire that is low on air. Positive scrub radius is when the tire contact patch is outside of the SAI pivot, while negative scrub radius is when the contact patch is inboard of the SAI pivot (front wheel drive vehicles usually have negative scrub radius).

If the brake on one front wheel is not working, with positive scrub radius, stepping on the brake will cause the steering wheel to try to rip out of your hand. Negative scrub radius will minimize that effect.
Scrub radius is designed at the factory and is not adjustable. If you have a vehicle that is pulling even though the alignment is correct, look for something that will affect scrub radius.

MPFI (Multi Point Fuel Injection)

The fuel injections were used to meet stricter emission norms as it keeps pollutants to bare minimum and derives the maximum performance out of a vehicle by squeezing out the maximum mileage even from the last drop of fuel that goes into the engine.

M.P.F.I. means Multi Point Fuel Injection system. In this system each cylinder has number of injectors to supply/spray fuel in the cylinders as compared to one injector located centrally to supply/spray fuel in case of single point injection system.
MPFI system injects fuel into individual cylinders after receiving command from the on board engine management system computer or Engine Control Unit (ECU).

Advantage of M. P. F. I.

(1) More uniform A/F mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. Vibration from the engine equipped with this system is less, due to this the life of engine components is improved.

(2) No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system.

(3) Immediate response, in case of sudden acceleration / deceleration.

(4) Since the engine is controlled by ECM* (Engine Control Module), more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level.

(5) The mileage of the vehicle will be improved.

ECM (Engine Control Module) and its function

The function of ECM is to receive signal from various sensors, manipulate the signals and send control signals to the actuators.

Sensors; Sensing different parameters (Temperature, Pressure, Engine Speed etc.) of the engine and send signal to ECM.

Actuators; Receives control signal from ECM and does function accordingly (ISCA, PCSV, Injectors, Power Transistor etc.)

Case I: If ECM fails to send control signal to all actuators then the engine won’t get started.

Case II: If ECM fails to service from all sensors then also the engine won’t get started.

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FUNCTION

This valve controls twin line brake system on a trailer from the towing vehicle fitted with Dual Brake System and the Hand brake valve for Spring brake actuators.

In addition, this valve also helps to apply the brakes automatically in the trailer when service brakes are applied on the tractor by exhausting the supply line (12) in the event of failure in the service line (22).

DESCRIPTION

Trailer control valve mainly consists of a Direction control valve and a trailer control valve.

Direction control valve has a valve body housing a piston assembly in the top bore with a spring and cover and secured in position by a circlip. This valve has an inlet, a passage for connecting the inlet to the trailer control valve and two more passages in which one to chamber connecting to service line (22) and the other to chamber connecting to Primary delivery line (41). This valve is secured onto the middle body of the trailer control valve.

Trailer control valve has a Upper body, a middle body and a Lower body.

Between the upper and the middle body a relay piston assembly with a return spring is located. The relay piston assembly has another piston with a spring, a spring guide and an adjusting screw in the bore and secured by a circlip.

In the middle body top bore and below relay piston assembly an emergency plunger assembly is located. The emergency plunger assembly has a spring loaded valve and a piston located in the bottom side and secured in position by a circlip. A diaphragm with upper and lower follower is located on the other side of the piston and secured by a flat hexagon nut. The outer lip of the diaphragm is located between the middle and the lower body. The free end of the piston is guided in the bore of the lower body and an exhaust check arrangement is secured to the lower body.

The upper body has a port (41) connecting to primary delivery line from Dual brake valve and a passage connecting to Direction control valve.

The middle body has a passage connecting to the inlet (1) from Direction control valve, supply port (12) and Service port (22) connecting to trailer, port (43) connecting to the delivery line of Graduated hand control valve and a passage connecting to Direction control valve.

The lower body has a port (42) connecting to the secondary delivery line from Dual brake valve.

CHARGING ( AIR SUPPLY TO TRAILER & BRAKES OFF POSITION)

· When the braking system is charged, the air supply enters through port 11 of the Direction control valve and acts at bottom of the piston pushing it to the upper stop against the spring force.

· The air supply goes to the supply line through the chamber connecting to port 12.

· If the tractor is coupled to the trailer, the trailer Reservoir is getting charged through the Relay emergency valve fitted on the trailer.

· In this process, air pressure acting below the emergency plunger moves it along with the valve upwards and the valve comes into contact with the piston closing the exhaust passage and subsequently opening the inlet passage, allowing the air supply to service line through the chamber connecting to port 22. This leads to brake application in the trailer.

The brakes are applied both in tractor and trailer as long as the Graduated hand control valve is in “BRAKES ON” position

· When the hand brake is released ( i.e. Graduated hand control valve in “BRAKES OFF” position ) air is supplied to chamber through port 43.

· Air pressure in the chamber acting on the upper side of the diaphragm pushes the piston downwards along with the emergency plunger. This leads to closing of inlet passage and subsequent opening of exhaust passage allowing the exhaust of air from the service line connecting port 22 ; thereby releasing the brakes in the trailer.

· At the same time, the spring brakes in the tractor are also getting released by air supply through Graduated hand control valve.

Brakes partially applied ( Predominance )

In brakes partially applied condition, air pressure in the chamber connecting to port 22 depends on the pressure acting on the relay piston (36) and the preload of the spring (35).

The preload of the spring (35) can be adjusted by the screw (32).

The preload of the spring is set to ensure that the outlet pressure in port 22 is higher by 0.5 ± 0.2 bar as compared to pressure at port 41.

The operation sequence from 1 to 4 continues and the air pressure acting below the relay piston (36) and piston (30) in chamber connecting to port 22 when exceeds 0.5 ± 0.2 bar as compared to the pressure in chamber connecting to port 41, the piston (30) alone moves upwards overcoming the preload of spring (35) and closes the inlet preventing further charging of chamber connecting to port 22.

This is the predominance position.

Secondary

At the same time as air enters port 41, air from secondary delivery of Dual brake valve also enters chamber connecting to port 42 and acts below diaphragm (44).

However, the pressure in chambers connecting to port 22 and port 43 acting above the emergency piston (26)and diaphragm (44) respectively is greater and the position of the piston is unaltered.

If brakes are partially applied, the pressure that builds in chamber connecting to port 22 again forces emergency piston (26) downwards. Thus the inlet passage closes and a balanced condition is reached.

Secondary failed

· When the brake is applied on the tractor, air is supplied to port 41 and its chamber.

· Air pressure in chamber acts on relay piston (36) and piston (30) pushes the pistons together downwards, thereby the piston (30) comes into contact with the valve (25) closing the exhaust passage and subsequently opening the inlet passage, allowing air supply into chamber connecting to port 22. (i.e. into the service line of the trailer )

· This leads to brake application in the trailer.

If the secondary of the Dual brake valve fails, operation of the valve is controlled by air from primary. In this case, the operation of the valve is with predominance

Primary Failed

· When brake is applied on the tractor, air is supplied to port 42 and its chamber.

· Air pressure in the chamber acts below the diaphragm (44) and pushes the emergency piston assembly upwards; thereby the valve (25) comes into contact with piston (30) closing the exhaust passage and subsequently opening the inlet passage allowing air supply into chamber connecting to port 22.(i.e. into the service line of the trailer )

· This leads to brake application in the trailer.

If the primary of the Dual brake valve fails, operation of the valve is controlled by air from secondary. In this case, the operation of the valve is without predominance.

Hand brake application

· When the Graduated hand control valve is in “BRAKES ON” position, air from the chamber connecting to port 43 and also hand brake line of Spring brake actuators is depleted through Graduated hand control valve.

· Automatically the relay piston assembly is pushed up by the air pressure in chamber connecting to port 12 and inturn the valve (25) gets into contact with piston (30) closing the exhaust passage and subsequently opening the inlet passage, allowing the flow of air into chamber connecting to port 22. ( i.e. air is supplied to service line of the trailer )

· This leads to automatic emergency brake application in the trailer.

Service line of trailer failed

· In a running vehicle if the service line of trailer breaks from port 22, no air pressure builds up in chamber connecting to port 22 when the service brake on the tractor is applied.

· The piston (10) is then pushed downwards by the air pressure in chamber connecting to port 41 and the flow of air supply from port 11 to port 12 is metered (reduced) by reducing the flow passage from 8 mm dia to 2 mm dia.

This is the Dumping operation.

· At the same time, air pressure in the chamber connecting to port 41 pushes the relay piston (36) and piston (30) together downwards and simultaneously pressure in chamber connecting to port 42 acting on the bottom of the diaphragm (44) pushes the emergency piston assembly upwards.

· Thus the valve (25) comes into contact with piston (30) closing the exhaust passage and subsequently opening the inlet passage.

· This helps to deplete air from chamber connecting to port 12 and the supply line of trailer through the point at which the service line failed, resulting in automatic emergency brake application in the trailer.

The pressure in the supply line of the trailer ( port12 ) comes down to 1.5 bar in less than 2 seconds.