347 Cylinder head some overall design considerations
The choice between cast iron or aluminium for the cylinder head is not simple. Aluminium has the advantages of light weight, high thermal conductivity, and ease of production to close tolerances by gravity or low-pressure diecasting. On the other hand, aluminium is more expensive than iron, tooling Fig. 3.37 At low speeds, a hinged flap deflects all the incoming air through the smaller of the two inlet valves in the Toyota 1.35-litre three-valve engine Fig. 3.37 At low speeds, a hinged flap...
Sleevevalve and special engines
Interest in the reciprocating sleeve valve has persisted throughout the history of the automobile engine, and though not now so widely used as in the early days of the Burt-McCullum and Knight patents, the single sleeve still has many strong adherents, while later metallurgical advances made possible such exacting and successful applications of the single sleeve as the Bristol Perseus and Napier Sabre aircraft engines. The double sleeve has become obsolete owing to its greater cost of...
81 Perkins P3 diesel engine
This engine was developed for installation in or as a conversion unit for light commercial vehicles and tractors. Its attraction was the flat torque characteristic and fuel economy of the diesel engine. Prior to this, diesel engines were ruled out for this type of vehicle because of the difficulties associated with the design of injection equipment for them and obtaining satisfactory combustion characteristics in small cylinders. The solution to the problem then appeared to be reducing the...
1112 SU carburettor type HIF
The HIF Horizontal, Integral Float Chamber carburettor was designed specifically to meet the requirements for exhaust emission control. At the same time, a noteworthy degree of compactness has been achieved by arranging the float and float chamber concentrically with the jet tube, as can be seen from Fig. 11.24. With this arrangement, too, the petrol level in the float chamber, immediately beneath the jet, is only minimally disturbed by changes in inclination of the vehicle, braking,...
629Details of the Minimec pump
The Minimec is available for three-, four-, six- and eight-cylinder engines, and is produced with alternative camshaft lifts of 7 and 9 mm, as compared with the Majormec, available in only four-, six- and eight-cylinder versions, which has lifts of 10 and 11 mm. Figure 6.25 shows the six-cylinder version of Minimec. For some applications, however, the housings for the pump and governor are bolted together instead of in one piece. Fig. 6.25 Minimec pump for 6-cylinder engines Fig. 6.25 Minimec...
418The ASSYST maintenance system
To fine tune oil change intervals, Mercedes have introduced what they term the ASSYST system. A computer-controlled instrument on the dash fascia indicates when an oil change is needed. Its reading is based on how hard and how frequently the car is driven with a cold engine. One advantage is the avoidance of unnecessarily frequent oil changes, and thus conservation of oil furthermore the engine is protected against wear arising from failure to replace oil when it really is necessary to do so...
1224 The GM Multec singlepoint system
Many features of the GM Multec single- or throttle body and multi-point injection systems are similar to those of the Bosch Mono-Motronic and Motronic systems respectively. A single-barrel, single-point, or TBI, system is illustrated in Fig. 12.36, though twin-barrel versions are also available if required. From the submerged twin-turbine-type pump, fuel is delivered at a pressure of 0.83 bar and rates from 19 to 26 g sec, through a 15 m filter to the a Plug-in calibration software EPROM d Idle...
4215 Composite leaf springs
In the early nineteen-seventies GKN began its development of leaf springs made of composite materials and, in late 1986, was the first to go into large quantity production, with a design illustrated in Fig. 42.13. Very high strength Fig. 42.12 Alternative multi-leaf a and taper-leaf b spring assemblies with helper springs designed for mounting on common fixing on a Scania range of chassis Fig. 42.12 Alternative multi-leaf a and taper-leaf b spring assemblies with helper springs designed for...
435 Single transverse link
What might be described as a single transverse-line system was used for the front suspension of the Allard vehicles in the nineteen-fifties. In effect, the front axle beam was divided in the centre, where each half was pivoted to the chassis frame. Coil springs were interposed between the outer ends of these half-axles and the frame. Drag loads were taken by two radius rods, both pivoted beneath the centre of the front transverse member of the frame and extending rearwards and outwards to a...
315 Multiplate clutchtype traction control device
For cars, the most commonly used automatic device is a limited-slip mechanism incorporating some sort of clutch. The aim is at introducing into the differentially geared coupling between the two halfshafts a degree of friction which will not only prevent one wheel from spinning freely, but also, by reacting the input torque to that wheel, provide for the transmission to the other wheel a torque equal to that arising from the frictional resistance. The multi-plate clutch type is the most popular...
4034 ZF Servolectric system
The ZF Servolectric system is powered directly by an electronically controlled motor. Thus, it dispenses with hydraulics and the consequent complexity of Fig. 40.55 The pinion mounted layout is the more compact, and installation can be easier Fig. 40.55 The pinion mounted layout is the more compact, and installation can be easier Fig. 40.57 Section through the worm drive, showing the torsion bar and torque sensor Fig. 40.57 Section through the worm drive, showing the torsion bar and torque...
2122 Stirling engine
The Stirling engine, invented by Robert Stirling, first built in 1816 and subsequently produced on a small scale, is not an internal combustion power unit. Its working gas is cycled in a closed circuit, passing through a heat exchanger on the way round. Gases such as hydrogen, helium and freon have been used in the closed circuit. Originally, it was a viable alternative to the steam engine, for example in marine propulsion, but it has yet to be proved competitive with the internal combustion...
2816 ZF HP500 fully automatic transmission
As can be seen from Fig. 28.24, the ZF HP500 automatic transmission has a hydraulically-actuated lock-up clutch in front of the torque converter. Its lock-up mechanism is engaged automatically to lock the impeller and turbine wheels together, to give direct drive, at a predetermined ratio of turbine-to-engine speed. However, a kick-down switch actuated by the accelerator pedal unlocks them again to provide extra torque when called for by the driver for climbing a hill, or overtaking on one, in...
645 The GM unit injection system
In basic concept, the GM unit injection, Fig. 6.55, bears some similarity to the Cummins PT system just described, but it differs in many respects. First, there is no separate unit housing all the control functions instead, each injector, Fig. 6.56, houses what is virtually a single element of a jerk pump, such as that illustrated in Fig. 6.27, and injection is controlled by a multisegment toothed rack that extends the full length of the head from the foremost to the rearmost injectors. From...
4026 Power assisted steering basic principles
For two reasons, power assisted is preferable to powered steering. First, with power assistance, the driver retains a degree of feel of the road, and this can be especially useful in icy conditions. Second, if the power fails, the driver can instantly exercise control directly, although admittedly the effort required becomes significantly and, in some instances, considerably greater. The need for power assistance is most obvious on heavy commercial vehicles, on which it offers two main...
718 The Lucas EPIC electronically controlled pump
The Lucas EPIC injection system, Fig. 7.36, was conceived in the late 1970s and design and development work on it began in the 1980s. This system was first installed on a production engine in 1991. It was designed for application to a distributor type pump to deliver at pressures of up to 1100 bar for high speed direct injection light duty engines with three, four and six cylinders up to 0.75 litres per cylinder. Maximum speeds of up to 4500 rev min were contemplated and, subsequently, medium...
1013 Air bleed compensation
As has been previously stated, air bleed compensation can be incorporated in the compensating jet well. However, to simplify the explanation, we shall describe how it functions as the sole method of compensation in a main jet. A good example, which was incorporated in some of the early Solex carburettors, is illustrated in Fig. 10.7. An advantage of using this device is that only one jet is needed. As can be seen from the illustration, the jet D is drilled in the lower end of a thimble-shaped...
Torque converters and automatic gearboxes
A torque converter is a device which performs a function similar to that of a gearbox, namely, to increase the torque while reducing the speed, but whereas a gearbox provides only a small number of fixed ratios the torque converter provides a continuous variation of ratio from the lowest to the highest. Constructionally, a torque converter is somewhat similar to a fluid flywheel from which it differs in one important aspect, namely, in having three principal components instead of only two....
1214 Bosch KEJetronic system
The KE-Jetronic system, Fig. 12.20, is similar to the K-Jetronic except that it has a simple diaphragm-type fuel pressure regulator, in place of the warm-up regulator, to maintain a constant primary pressure above the control plunger in the fuel distributor of Fig. 12.17. Another change is the flange-mounting of an electro-hydraulic pressure actuator on the fuel distributor, to regulate the pressure in the supply to the lower chambers of the differential pressure valves. Thus, whereas in the...
727 The incremental pressure stages
Inside the pump the fuel is contained in three compartments, each at a different pressure. These are lift pump, supply pump or high pressure and injection pressure. Different vehicles may have different types of lift pump, but the supply pump, Fig. 7.56, is common to all installations of the VP44 and is of conventional design. Its vanes are forced radially outwards by centrifugal force, supplemented by coil type compression springs. The function of these springs is to ensure that, even when the...
176Boiling point vapour lock and ice formation in induction systems
Vapour lock occurs when pipes or fuel pumps become over-heated. The low pressure both inside the pump and in the pipeline between it and the tank reduces the boiling point of the fuel, so heat transmitted to these components by, for example, the exhaust manifold causes it to vaporise. Because pumps are designed to deliver liquids, they cannot cope with vapour consequently, the supply of fuel to the engine is interrupted, causing it, at best, to run roughly and, at worst to stop. Vapour lock is...
726 Bosch VP44 radial plunger type pump
The VP44, Fig. 7.55, is described by Bosch as a high pressure electronically controlled radial plunger type pump. Its housing is divided by a diaphragm into two chambers. One, at fuel lift pump delivery pressure, accommodates the drive shaft and all the components mounted on it. The other, at a much higher pressure, houses the distributor head and shaft. In the base of the pump housing is the device for regulating the timing of the start of injection, together with the pulse valve which...
632 Governors
The C type governor employed on the Minimec pump, Fig. 6.26, can be seen in more detail in the top diagram. Cages are available with pockets for accommodating two, three, four or six weights, Fig. 6.34. In each instance the weights pivot in the corner between the back of the cage and its peripheral flange. The cage is bolted either directly to a flange on the camshaft Fig. 6.33 The curve ABCD shows the full load fuel requirement for a turbocharged engine and the dotted line the fuel supply as...
402 Multiwheel vehicles
With six-wheel vehicles, perfect steering geometry is unobtainable because the two rear axles always remain parallel. An assumption is made, therefore, that the vehicle turns about a centre on an axis midway between and parallel to those of the two rear axles, and the steering linkage for the front axle is laid out on this basis. There will of course be some tyre scrub on both rear axles, but this is accommodated by the lateral flexibility of these tyres. Even so, the two back axles are always...
634General principles of engine speed control
As has already been explained, cut-off and spill timing determines how much fuel is supplied to the engine and therefore, at any given speed, the torque and power developed. However, direct control of the fuelling by a simple linkage between the accelerator pedal and rack, or control rod, in the injection pump would not be acceptable. This is because, owing to viscous friction and other losses, the rate of flow of air into the engine does not increase linearly with speed, even in naturally...
4035 Honda EPS and VGR systems
Honda first applied a mechanically driven hydraulic pump type power assisted steering rack and pinion gear to its NSX car in 1990. In 1991, to save energy, an electrically driven hydraulic pump replaced the engine-driven one and a rotary spool type valve was introduced for the system installed on the Honda Civic. Their first electrically powered system was introduced in 1993, and speed dependent power assistance in 1995. The latter system combined reduced steering effort at low speeds with...
396 Teves Mk IV ABS and traction control
In Fig. 39.12 the Teves Mk II system, for the Ford two- and four-wheel-drive cars, Sections 39.4 and 39.5, is compared diagrammatically with the Mk IV system. Cost reduction, to render the equipment suitable also for less upmarket cars, was the primary incentive for the Mk IV development. The principal economies were the substitution of a vacuum for a hydraulic servo, or booster, and the use of a pump of higher output, at extra cost, to obviate the need for an accumulator. With the abandonment...
49 Jaguar AJ6 engine
When the oil crises of the early nineteen-seventies posed a threat to their V12, Jaguar originally set out to, in effect, remove two cylinders from each block to produce a V8 on the same machining lines. However, the characteristic secondary out-of-balance forces of the V8 could be counteracted only by the incorporation of a balance shaft, which so changed the shape of the crankcase that the enormous cost of introducing an entirely new one would have been entailed. Next, they produced, in 1971,...
732 Stanadyne rotary distributor pumps
The forerunner of all the pumps of this type so far described was the invention sold in 1947 to the Hartford Division of Stanadyne by Vernon Roosa. Two features distinguished this invention one was the substitution of two opposed plungers for the then universal arrangement of one plunger for each engine cylinder the other was the use of inlet, instead of spill, metering. The latter feature meant that the unit was almost self-governing, so that only a simple low cost governor was needed. By...
325 Builtup crankshafts
Two examples of the built-up type of crankshaft are shown in Figs 3.17 and 3.18. In Fig. 3.17 is shown one throw of a crankshaft in which the crank webs are permanently shrunk on to the journals the case-hardened crankpins being secured in the split webs by the clamping bolts shown. The other example, Fig. 3.18, is the crankshaft of a special racing engine. The webs of the shaft are formed of circular discs A and B, the A discs Fig. 3.16 Cast crankshaft for Ford V-eight Fig. 3.16 Cast...
617The Phaser combustion chamber
Of major interest in the Phaser was the combustion chamber in its piston, which Perkins termed the Quadram design. This chamber, as can be seen from Figs 6.10 and 6.11, is of approximately toroidal form but with four lobe-like cavities equally spaced around it. Basically, the incoming air is directed tangentially into the cylinder to form a vortex swirling round its axis. Then, as the piston comes up to inner, or top, dead centre, this vortex is forced into the combustion chamber. Because the...
1023 Solex progressive starter
There are several variants of the progressive starter first introduced by Solex. All have been actuated either manually by a pull-out control on the dash or automatically by a thermostatic device such as a bimetal spring. The original Solex unit had simply an on-off control, while later versions were progressive, having positive-feel two- or three-position rotary disc valve controls. A slightly different application of the multi-hole disc valve principle, can be seen in Fig. 11.27. In Fig....
317Bearing materials
Undoubtedly whitemetal has the best bearing properties. However, its fatigue strength is limited so other alloys have to be used for many modern highlyrated engines. Properties of bearing metals are set out in Table 3.2. Babbitt invented whitemetal in 1839. It contained 83 tin, 11 antimony and 6 copper. The hard copper-antimony particles suspended in a matrix of soft copper-tin alloy give good wear resistance plus the ability to embed solid abrasive particles that would otherwise wear the...
273 Epicyclic gear ratios
For ease of recognition of the various gears in all that follows, the annulus gear is called A, the planet carrier C, the sun gear S, and the planet gear P, and it is assumed that the gears have respectively A, S and P teeth. If either end of the planet carrier arm is integral with a tubular shaft and coaxial with the gear shaft at that end, the arm can be used as either the input or output. First, take the case of the planet being fixed and the carrier arm, serving as the input, turned through...
318 ZF limited slip differential
The ZF cam-and-pawl type unit, Fig. 31.8, has the advantages of simplicity, and therefore inherently low cost, and light weight and compactness. On the other hand, it is liable to wear fairly rapidly if worked hard. It is particularly suitable for application to racing cars, where rapid wear is immaterial because it is normally not required to last longer than a few races. Moreover, racing drivers are all highly skilled and can cope with the steering and other effects associated with its jerky...
36AEconoglide piston
A major advantage of the slipper and articulated types of piston is the small areas of their skill relative to those of the more conventional piston and, in consequence, reduced oil drag between them and their cylinder bores. However, they are more complex and therefore not only costly but also the potential for weight reduction is very limited. An even simpler way to reduce the drag would be to shorten the skirt, but this would lead to piston tilting, with high contact loads on the top and...