Search

The problems confronting the chemist in control of water treatment for an industrial boiler plant are very complex and dictated to a great extent by the pattern of plant operation. An interesting field of study is presented, particularly where the plant is modern in design and very extensive in the service it provides. The author has concerned himself principally with the problems of water supply and treatment at Aylesford Mills, as these are very typical of those which occur in other large industrial undertakings. Details are given of the feed water treatment plant for the medium- and high-pressure boilers, consisting of primary sedimentation units using lime, ferrous sulphate, and alum as chemical additives, followed by a filtration stage. This section of the plant is followed by a dual system comprising three base-exchange softener units and a fully automatic demineralization plant. The interesting features of fully automatic regeneration of the demineralization plant are discussed, together with the author's experience in operating this plant. Emphasis is placed on high standards of feed water treatment and the principles of the system adopted. Sodium sulphite and tannin are added as chemical deoxidants on medium-pressure plant. Hydrazine, together with a neutralizing amine, are used on the high-pressure boiler installation. The author concludes the paper with comments on the subject of boiler corrosion.

Because of the complexity of operation of a paper machine, a simulation of operation would provide three avenues through which better startup and operation could be obtained: (1) engineering evaluation, (2) operator training, and (3) control-program evaluation. Prior to the startup of a new high-speed paper machine, a simulation of the stock system where the suspended fibers are formed into a sheet of paper was undertaken. Basic information on the steady-state and dynamic be havior of such a system was obtained on a highly instru mented paper machine having components similar to those of the new machine. The system was analyzed one component at a time to fit available theoretical equations with minor modifications. This allowed reasonable extrap olation and reassembly of the system to describe the new machine. An important factor in describing such a system was the transport lag in the pipelines. This facet of the simulation was accomplished with prewired Padé approximations of these lags. A second important characteristic in describing a paper machine in real time is the long time-constants involved in the rates of change. These may run as long as 10 minutes. A replica of the main control panels was constructed for use as a training aid for the operating crews of the new machine. The panels were programmed on the computer to respond to upsets and grade changes as part of an inten sive training program for the operators. Exploitation of the simulation system is still in progress. It is evident, however, that the smooth startup resulted from careful planning and effective operator training.

This paper presents a technique for simulation of the stock preparation and Fourdrinier dynamics which is flexible, convenient, and detailed enough to allow the user to study physical process modifications and transient response dur ing upsets and "furnish" (fibers with different character istics, fillers, dyes, etc.) changes and to evaluate simplified mathematical models and control schemes. The technique uses digital simulation in a block diagram form, each block of which corresponds to one type of physical unit in the process (e.g., cleaner or tanks). Simu lation of a particular process then involves specification of the particular parameters of each physical unit together with the way in which they are interconnected. Individual components of the furnish may be traced through the whole process. A complete wet-end configuration, including the white water recovery system, is simulated using the technique described in the paper, and typical results obtained during grade changes and disturbances are presented.

During the last two decades both the speed and width of paper machines have increased considerably. This has resulted in the adoption of many devices which prior to that time were still looked on with doubt. The increase in width and weight of the rolls of modern newsprint machines has made the removable wet end practically standard. Similarly the increase in speed has only been made possible by the use of the projection slice, suction couch, and press rolls, which are being fitted with success to machines of all types. The shells of suction rolls must be free from blowholes and this has entailed the use of centrifugal castings, and has been the means of developing their technique. A further development is the vacuum-forming paper machine, probably the most revolutionary modification of the Fourdrinier machine yet proposed. The two-wire machine gives a paper free from any wire mark, and recently a wire has been produced which goes some way towards the elimination of the wire mark. Electric drives arc nearly standard on all new machines.

The basic criteria for development of a suitable per cent moisture gauge for paper are discussed and the paper industry requirements analysed. The theory of operation for the infra-red gauge is explained and the various components of the system described at length. Installation methods for fixed point and traversing mechanisms are set forth. The significance of the calibration technique being used is discussed. A wide range of current installations is described and the extension of applications on the paper machine suggested.

SummaryThe electrophoretic behavior of serum leucine aminopeptidase (LAP) in normal individuals, in pregnancy, and in patients with hepatobiliary disease was investigated with paper electrophoresis technics. In normal serum LAP migrated as a single component in the α1-globulin fraction. In patients with elevated serum LAP activity due to hepatobiliary or pancreatic disease supplementary peaks of enzymatic activity were demonstrable in other protein fractions. Thus, in jaundiced patients with carcinoma of the head of the pancreas, liver metastases, biliary atresia, acute hepatitis, and drug-induced jaundice, additional activity was observed in the β-globulin fraction. In some patients with hepatitis additional activity was observed in the α2-globulin as well as β-globulin. In common duct stone additional activity in the albumin fraction was a consistent finding. In early pregnancy the electrophoretic pattern of LAP was similar to that observed in normal serum, whereas during the third trimester LAP activit...

The problem posed was the design of an engine having a taxable horsepower of 5 for a private car with rear wheel drive and weighing 700 kg when empty. It was also required that there be two main variants derived from this: an engine for a sports car and one with a larger cubic capacity for a utility vehicle. The paper describes how this problem was approached. After a re-examination of why the four-stroke carburation engine is very popular, the number and arrangement of the cylinders in relation to the cooling is considered. Apart from certain arrangements imposed by the fitting of the engine in the car, the simplest form of construction is that of the water-cooled engine with the cylinders in line. The cooling circuit is sealed. The arguments enabling the stroke and bore to be decided upon, first within the limits of a given cubic capacity and then by removing this restriction, are then expounded. The conclusion is that the bore should be as small as possible compatible with the performance called for. The following technological details of the engine, which has been designed with two possible cubic capacities—956 and 1100 cm3 by varying the bore, are then considered: design of the cylinder block with wet liners; piston, connecting rod, crankshaft assembly; arrangement of valves, camshaft, carburettor and manifold; engine sealing and filtration.

A discussion is given of the basic physical processes occurring in magnetohydrodynamic (MHD) generators. In designing a generator two parameters are of importance, namely, the power output per unit volume and the isentropic efficiency ñs which is a measure of the departure of the generation processes from the ideal. It is shown that the maximum electrical output per unit volume of gas is ñs(1-ñs)θ u2 B2 where θ is the electrical conductivity, u the flow speed down the duct, and B the magnetic field strength. The paper describes how the isentropic efficiency depends on the load characteristics, how to calculate the electrical conductivity, the effect of a strong magnetic field on the electrical conductivity and the optimum shape of an MHD duct. A brief account is given of the progress in the development of experimental generators and of the practical problems still to be solved.

The paper gives the history of the conception and design details of a mass-produced four-cylinder 803 cm3 engine, its redesign to 948 cm3 and the design of a twin-carburettor version. Finally a further redesign to increase the capacity to 1147 cm3 for both single- and twin-carburettor versions. An initial appraisal was made of the type of unit required to power a small family saloon car. Engine performance requirements were established from a performance curve of the vehicle obtained from frontal area aerodynamic coefficient, estimated weight, etc. The configuration of the unit was fully investigated, the number and disposition of the cylinders, type of cooling, position of valves and type of valve gear were all explored, bearing in mind technical requirements, cost and ease of production and production plant requirements. Having decided upon a four-cylinder in-line liquid-cooled unit, a detailed description is given of the reasons for the design configuration of the major components and the disposition of the ancillary equipment. The need to extend the range of models of this vehicle brought about the first increase in capacity to 948 cm3 and design modifications are enumerated. A twin-carburettor version was a further requirement and design and development details are discussed. With the introduction of a completely new design of motor car using this power unit, the road holding and general handling characteristics of the vehicle were so outstanding that improved engine performance became a necessity to match the above qualities. The methods of increasing performance are discussed and the reasons given for the necessity to increase capacity. In view of already established transfer machinery for all major components, the minimum of change was essential and a history of the design and development of the unit is given. It is shown that careful study of existing equipment is vitally necessary when making extensive design changes. First designs made the minimum of change and only when test work showed shortcomings were further changes made. A series of designs and tests finally achieved a sound design giving excellent results from extended tests. This process established that all the modifications were vitally necessary to achieve the performance and reliability necessary for the engine to have a further period of production and enable progressive development to be successful.

This paper contains the results, plotted non-dimensionally, of extensive tests carried out on a 1–625-in diameter grinding machine spindle lubricated hydrostatically. The horizontal spindle is directly coupled to a variable-speed motor at one end and loaded vertically at the other. The spindle is not constrained to rotate at arbitrary eccentricity values, but is able to seek an equilibrium position depending upon oil flow and rotational speed. The attitude, oil film thickness, and eccentricity are measured by mutually, perpendicular capacitance probes arranged in the bearing housing. The results indicate considerably decreasing load-carrying capacity as the rotational speed increases, because the hydrodynamic effect tends to centralize the shaft in the bearing housing, thus nullifying the hydrostatic effect. Paradoxically the same effect causes an increase in oil film stiffness as it is generally defined. A summary of earlier work is included, notably that of Raimondi and Boyd who considered bearings of fixed eccentricity, and the paper also presents a theoretical analysis based on the pressure- and velocity-induced circumferential flow theories.

The damping action of a plain slideway is considerably influenced by a number of parameters and is difficult to assess. It has been necessary, therefore, to obtain experimental data from adequately scaled experiments. The major emphasis is placed on the influence of polar additive lubricants as they offer considerable advantages in stabilizing feed drives at low feed speeds. This paper describes an investigation into the mechanism of the interaction between vibration in the direction of motion and the vibration normal to the plane of the slideway interface. Steady-state characteristics do not give an adequate guide to the damping action of a machine tool slideway. All the work discussed in this paper is restricted to vibration amplitudes that do not cause the instantaneous velocity of the feed drive to be reversed.

The first part of the paper describes initial test results obtained on an experimental installation of the differential compound engine. The initial tests broadly confirm the predicted torque–speed and power–speed relationships which are appropriate to traction-type prime movers, and are intended to eliminate the need for multi-ratio gearboxes or their hydrostatic or hydrokinetic equivalents. The second part of the paper contains performance predictions based on certain cycle and component modifications such as interburning before the auxiliary turbine, and variable nozzles.

This paper deals essentially with flexible wrapping materials and their performance on packaging machinery. The emphasis throughout is on the packaging media but the demands made on them by machines are given prominence. The basic principles of the main types of machine are enunciated and illustrated with simple flow diagrams. These show the passage of the wrapping material through the machine and the text isolates the different sections and the wrapping problems involved. For example, the feeding, forming and closure sections of a machine are examined and such properties as slip, tensile strength, elongation and heat-sealability of wrapping materials are considered in relation to them. The paper opens with an historical survey of packaging, packaging materials and packaging machinery. The economic trends which shaped the packaging industry are presented and general developments in packaging materials and machines are traced from the turn of the century. Some comments on the functions of packaging and its part in the industrial scene are made. The packaging media covered include paper, cellulose films, aluminium foils, plastic films and the main forms and combinations of them. The production, properties and uses of these materials are outlined but the main emphasis, as stated above, is on their machinability. Current developments in wrapping materials and machine principles are discussed and some effort is made to forecast trends in flexible packaging generally.

This paper briefly describes early unsuccessful attempts to produce an e.p. turbine oil based on an active sulphur e.p. additive, and describes experience with a successful oil based on chlorinated paraffin wax. Anti-scuffing capacity is discussed, particularly in relation to conditions of shock loading and running time. The effect of the oil on increasing plastic flow in soft gears, and thereby on pitting, is also examined. After discussing the demulsibility of oils in service, chemical effects are described in detail; namely, staining caused by the formation of β-FeO. OH deposit formation due to overheating of bulk oil and due to the overheating in thin films exposed to air. The latter relates to severe shaft damage owing to the formation of carbonaceous matter in bearing pedestal baffles, and recommendations are made towards design. The paper concludes with experiences of the wire-wool type failure of turbine thrust bearings, and present details of the oil/steel interactions found in the course of extensive full-scale rig work on the problem.

An account is given of the planning, construction and occupation of the Department of Mechanical Engineering at Brighton College of Technology. This College took over all the advanced studies of the Brighton Technical College and the paper describes the transfer of the old department and its establishment in a new building. The organization of planning consultation between architects and College is explained and the position of the Department in relation to the whole College is shown. Schedules of accommodation indicate the floor areas available and the expected student capacity. Description is given of the detailed design of individual laboratories involving work by all members of the teaching staff grouped in three sections dealing with Thermodynamics, Mechanics and Materials and Production Engineering respectively. The preparation and finance of the schedule of equipment and the purchasing, supply and installation arrangements are explained. Economy made necessary the transfer of some existing equipment and the organization of removal and reinstallation is described. A short description of the main features of construction of the building is given followed by details of services and furnishings. The final layout of the laboratories is discussed and criticized in the light of eighteen months' use. The paper concludes with general comments which may prove of value to others undertaking similar tasks.

The paper reviews the present state of knowledge and design techniques and attempts to provide a physical appreciation of the characteristics of bearing performance. The work which has been carried out recently in the United Kingdom, the United States, The Netherlands and Germany is examined and the paper attempts to relate this to experimental results and the practical engine. The possible relationships of components within the engine which affect the conditions of operation and parameters which could lead to improvement of these conditions are suggested and examined, and the possibilities of future work in exploring this area are indicated.

This paper presents an outline of the power and energy requirements of a human elbow and gives a discussion on the means by which these requirements can be met. Reasons are given for the choice of a system using batteries for energy storage and direct electric drive by a motor and gearbox. The gearbox is of an unusual type, using ‘harmonic drive’ elements, which permit the motor to be installed transversally at the elbow. The gear reduction unit is described in detail. The paper also discusses the problems inherent in controlling a motor with large stall current in such a way that most efficient use is made of the energy stored in the battery, and two control circuits are described which meet the requirements.

The development of implement control systems has been greatly influenced by the pattern set by the Te20 Ferguson tractor, and most three-point linkage draught control systems operate on the same principle. Such designs, whilst adequate for most purposes on level going, display poor depth control behaviour when traversing undulating ground. A full understanding of these systems has been limited by the absence of a mathematical theory capable of predicting their behaviour. This paper sets out to examine the problem in control theory terms. An experimental hydraulic control system has been built using pure draught force sensing, and its behaviour has been studied both mathematically and experimentally in the laboratory and in the field. To enable theoretical predictions of system behaviour to be made a second rig was constructed to study the transfer functions of implements. This rig can also serve as a simulator of field surface disturbances. The performance of the experimental system was compared with a popular commercial system using the second rig as a simulator and the results indicate that pure draught control sensing as used in the experimental system is feasible in practice. The paper concludes with a short discussion of alternative control strategies.

The main content of the paper is concerned with the way people compensate their driving behaviour for degraded vehicle stability. It also outlines briefly the background of man–machine simulation and the use of driving simulators in the U.S.A. The problem was investigated by means of a fixed base driving simulator at the Davidson Laboratory as part of a larger programme concerned with driver behaviour. The simulator has a two-degree-of-freedom analogue simulation of the vehicle dynamics. The display system is photographic using a real road film, and the vehicle is subjected to random appearing disturbances of the wind gust type. The disturbance, vehicle, and driver behaviour are recorded both as analogue and digital signals for experimental control and later data analysis. The paper describes and gives the derived results from an experiment with nine subjects, driving two vehicles, one understeer and one oversteer, simulated to be travelling at 60 mile/h. While driving, the vehicles were subjected to a random appearing gust spectra having a maximum amplitude equivalent to 10 mile/h. Methods of assessing overall driving performance and what the drivers did in the two vehicles are developed and the results, in terms of a driving error and a control response function, are presented. The driving error results show that, in general, drivers had significantly higher error scores with the over-steering vehicle. The driver control response function gives a measure of the reaction to the various disturbing frequencies of the disturbance. The results show that seven out of nine drivers had a control response function that was higher with the oversteering car. The remaining two subjects had the highest error scores with the understeering vehicle. A driving effort function is derived and it is shown that, with exceptions which are discussed, the driving error may be regarded as a function of driving effort. The results substantiate the hypothesis that the driver will try to compensate for degraded vehicle stability, but show that the compensation is only partial and increased errors result. The implications for real driving situations are that degraded vehicle stability, either of a basic vehicle or occurring during manoeuvring, will be only partially compensated for by the driver, and increased driving errors from the driver–vehicle system are likely to result. The techniques used for the simulator experiment are suitable with only minor modifications for real driving situations.

The objects of this paper are to demonstrate the use of the method described in Paper 6 and to give an indication of the effect of design parameters on the performance of a dynamically loaded bearing. An investigation into the main and big-end bearings of a diesel engine of modern design is described. The performance of a bearing is gauged by obtaining: (a) the minimum oil film thickness, (6) the maximum pressure developed within the oil, (c) the maximum load/projected area, and ( d) the bulk oil temperature rise. The influence of the engine design upon the big-end bearing performance for the particular engine under consideration is found by investigating the effects of the following parameters: ( a) bearing length-diameter ratio, (6) removal of centre-circumferential groove, ( c) inlet temperature, ( d) bearing clearance, and ( e) loading diagram. This last parameter is varied by changing in turn the piston mass, the connecting-rod mass, and the position of the connecting-rod centre of gravity. Finally, the effect upon the main bearing performance of various balance weight configurations is demonstrated. The usual assumption is made to obtain the main bearing loads: that loads imposed by a crank throw are equally distributed between neighbouring main bearings. General conclusions are made regarding the relative influence of certain bearing-design parameters upon the bearing performance.

The purpose of this paper is to review, necessarily rather superficially, the broad question of emissions from diesel engines and their relation to combustion as seen from an engineer's point of view. From the previous paper it will be realized that smoke is the emission currently under strongest scrutiny. Nevertheless, as gasoline engine emissions are brought under more rigorous control there also will be pressure to control unburnts, oxides of nitrogen, and other emissions from diesel engines.

The paper deals with the story of the engines intended for the smaller Fiat cars, starting with the ‘500’ model produced in 1936: all engines with displacements in the neighbourhood of 500 cm3. With small cars, especially of the utility class, the adaptability of the piston engine to a variety of design and space requirements is used to best advantage. The size, weight and displacement must blend with the design of the car as a whole; in turn, the design must feature the highest degree of simplicity compatible with the qualities required. It is, therefore, important for the engine of utility cars to be designed as a function of the general architecture of the vehicle. At Fiat, after a period in which economical cars of conventional design were produced, work was started along this line with the ‘500’ (Topolino) model in 1933–1934. The paper illustrates the design of this model and describes the reasons behind some of its engineering details, as well as the subsequent developments which led to the final solution. Also outlined are the more important designs of experimental engines studied as substitutes for the ‘500’ model: a transversal four-cylinder engine, with overhead camshaft, built in 1945, for a front-wheel drive prototype; an air-cooled, two-cylinder in-line engine, mounted transversally, for a rear-wheel drive prototype; an opposed two-cylinder engine, with longitudinal axis, in replacement of the previous unit; a two-cylinder in-line engine with longitudinal axis, finally chosen for the ‘New 500’ model introduced in May 1957. Also described are the further developments of the latter engine for the version with horizontally arranged cylinders suitable for underfloor application. The paper highlights the more interesting aspects regarding both the design and the experiments made and explains the principal reasons leading to the choice of given solutions and to the modifications which followed.

The paper states why air conditioning is necessary particularly in office blocks in cities, where noise, dust and heat from office machinery together with solar heat gain through large glass areas are experienced. The relatively small addition to building costs in incorporating air conditioning is shown. The distinction between air handling, ventilation and air conditioning is defined and the constituent parts of a complete air-conditioning unit are enumerated. The requirements in terms of fresh air needs, temperature and relative humidity for the normal applications of air-conditioning units are tabulated. A comparison of the main categories of air-conditioning equipment is made, dealing with high and low velocity as well as special laboratory type units. A typical performance specification is also given together with data sheets for collecting the necessary design data and cost comparisons. The paper concludes with a discussion on system design incorporating factory-made equipment and literature references.

This paper investigates the common factors which may account for the preference for plain bearings in parts of the driveline. Theoretical and practical performances are compared and discrepancies are detailed and rationalized where possible. The paper continues to show the need for more experimental data from which computed results might be modified to allow for aspects of the environment for which no precise mathematical model yet exists.

This paper reviews gas turbine cycles most favoured for vehicular use. It suggests the single-shaft turbine engine as a possible contender for a lower cost approach, where fuel economy requirements are not met by complexity of cycle but by operation at higher turbine inlet temperatures. The question, ‘Where does the engine end and the transmission begin?’ is discussed, and an example of an infinitely variable transmission is explored as a means for overcoming the performance deficiencies of the single-shaft machine. The paper examines the advantages and disadvantages of this type of turbine engine with respect to acceleration and torque characteristics, fuel consumption, engine braking, initial cost, and design for simplicity and high temperature.

The paper is set in a background of boiler commissioning for customers in power generating, industrial, marine, petro-chemical and oil-refining companies in Britain and overseas. Some of the problems encountered during the commissioning of a diversity of units employing solid fuel, oil fuels, naphtha, gas fuel firing, either singly or in combination, are discussed, and actual case histories detailed. The paper embraces difficulties experienced with the ignition of fuels, the control of flame shape, air distribution to burners, layout of fuel supply lines, safety circuits, and the necessity for close collaboration between the customer and the designer during the tender and contract stages, in order to avoid loss of availability, resulting from delays in commissioning or subsequent damage to equipment.

The installation and test procedure employed at the Road Research Laboratory for studying the performance of compaction plant is described. The results of tests on a wide range of equipment are summarized and an outline is given of some investigations of more fundamental factors likely to affect the performance of compaction plant. The author would like to acknowledge the help given by his colleagues and particularly Mr A. W. Parsons of the Laboratory who assisted in much of the work described in the paper. The work described in this paper was carried out as part of the programme of research of the Road Research Laboratory and is contributed by permission of the Director of Road Research. Reproduced by permission of the Controller of H.M. Stationery Office, Crown copyright.

This paper describes experience with glandless pumps on the S.G.H.W.R., both wet and dry stator types being included. The performance of the pumps is discussed and details given of the problems which arose in operations. Experience suggests that deposition in the pumps of radioactive corrosion products will not be a significant problem. The paper is in four parts: the functions, characteristics, and instrumentation of the pumps are outlined, followed by a description of some of the key results from commissioning tests.

Modern diesel engines are used in a wider variety of applications, installations, and environments than probably any other power unit. It is quite common for one engine type to be used for tractors, automotive, industrial, and marine purposes, with very little change to the basic engine. Considerable changes are necessary in the fuel-injection system, however, to meet the varying torque curve, speed range, and governing requirements. Operation over a wider range of temperatures and viscosities is often needed, and noise and smoke legislation have added further requirements. The paper outlines these problems and the compromises that must sometimes be made. Direct-injection and indirect-injection engine cases have been considered. The paper concludes with some comments on pre-setting fuel pumps for high-volume production.

This paper describes two different computer programs for the calculation of rolling bearing applications in an automotive driveline. The first program gives the effect of bearing preload or internal clearance on bearing deflections and nominal lives in bearing applications with taper roller bearings. As an example, the paper deals with a front hub bearing arrangement with two taper roller bearings used in a front wheel driven car, and also with a pinion of a final drive unit and a gearbox mainshaft incorporating two taper and one cylindrical roller bearing. The second program is used to determine the influence of misalignment and shaft deflection on the load and life of a deep groove ball bearing. To illustrate this effect the layshaft of an automotive gearbox is studied.

This paper investigates the reasons for the changing face of the gas industry and discusses the wide range of installations utilizing gaseous fuel for space and comfort heating. The gaseous fuels available in the U.K. are examined and the fundamental principles of combustion and control and the safeguards incorporated in appliances are outlined. The problems of conversion from town gas to natural gas are also dealt with. The main part of the paper is a review of types of gas installation used for space heating and cooling. Domestic, commercial and industrial installations and district heating are dealt with separately and the engineering and design details are given, supported by extensive references. Particular reference is made to installations peculiar to gas. The paper suggests a promising future for gas, and an attempt is made to indicate future trends in utilization and fuel costs.

This paper describes the various types of centrifugal compressor used in process plants, and continues to discuss the more important components of these compressors and particular design features which are required to overcome some difficult operational problems. Items of particular interest include a discussion on the latest form of compressor rotor construction, the techniques required for balancing a rotor at full speed, and a detailed analysis of shaft gas seals and problems that can arise with gas seals under certain operating conditions. The paper also describes such special subjects related to process plant compressors as compressor selection and design by utilization of computers, methods of reducing time to produce compressor orders by discrete stockholdings; types of driver and shaft couplings used for these machines, and test facilities employed for centrifugal compressors which can be utilized to reduce commissioning periods at site.

This paper describes in detail the flexible pin mechanism of load-sharing not only between adjacent planet wheels but also across the full tooth face of both sun and annulus mesh points. The history of a number of examples of gears in service is also described, and the paper concludes by showing the range of applications for this type of gearing, including the ultimate refinement of providing a drive with an infinitely variable ratio.

This paper reviews the types of tractor in use in West Germany and discusses the sales of new tractors over the last few years. It is shown that the interest in all-wheel drive tractors is steadily increasing owing to their higher power rating and improved tractive ability. The paper also comments on tractor equipment and design in relation to the proposed E.E.C. regulations for safety and performance, and concludes by summarizing some of the problems of tractor development.