Abstract: A vehicle clutch, when engaged, should have a predetermined clearance between its release bearing and its release plate. To disengage the clutch, a release bearing carrier sleeve is slideable to cause the bearing to contact the plate and then displace it axially. To indicate deleterious lack of clearance, the bearing has an electrically-insulating mounting and is connected to the vehicle's electric supply by a power line containing a warning light. The plate is inherently connected electrically to the vehicle's chassis, and the bearing thus acts as a switch. To prevent the light being illuminated when normal operation of the clutch occurs, the power line also contains an automatic electronic delay circuit.

Abstract: Tractors often have front ballast weights to counter-balance rear-mounted implements. These weights are usually contiguous parallel cast plates disposed in longitudinal vertical planes. Transversely aligned recesses are often provided in the front edges of the plates to form a towing mouth, and complementary semi-cylindrical grooves in the side faces of the plates form cylindrical holes intersecting the towing mouth, one such hole containing a hitch pin. Side loading is transmitted back to the weakest section of those weights carrying the hitch pin; and the hitch pin is a loose fit in its hole because the latter is formed by cast grooves. To avoid these disadvantages, the grooves are omitted and a clevis fitted partially within the recesses is clamped to the tractor frame by bolts passing through longitudinal holes in the respective weights and has upper and lower jaws with vertically aligned machined holes for the hitch pin.

Abstract: Tractor hydraulic power lift mechanisms may have automatic draft control signals fed back to them from lower link draft force sensing systems. One such system has two bowed rearwardly-extending leaf springs anchored to the tractor frame at their front ends, two laterally-spaced arms pivoted at their upper ends to the tractor frame and at their lower ends to the rear ends of the respective springs, a cross-bar universally supported by the lower ends of the respective arms and having two attachment points laterally offset from said arms to which the front ends of respective lower hitch links are universally connectible, and linkage for deriving a control signal from the fore and aft displacement of the mid-point of the cross-bar. However, the cross-bar is stressed in bending to the detriment of the control signal accuracy. To avoid this, a summating bar is universally connected between said arms and the control signal derived from a point on the unstressed summating bar.

Abstract: A very heavy vehicle may tend to run away on a steep gradient and as a result the engine is liable to be overspeeded with consequential risk of damage especially to its valve mechanism. The invention aims to prevent overspeeding by providing a servo mechanism operable automatically above a predetermined engine speed to apply an exhaust brake. The servo mechanism preferably comprises a centrifugal clutch normally held disengaged by springs and disposed on a shaft driven by the engine. Angular movement of the driven member of the clutch due to its engagement by engine speed in excess of the predetermined value is limited to, say, 60.degree. by a stop, and said member is mechanically linked to the operating means of the exhaust brake.

Abstract: An internal combustion engine of the reciprocating piston type has oil jets for cooling the pistons. The jets are fed by the pump which supplies oil to the engine's lubrication system. A valve in the feed line to the jets is arranged to close automatically when the pressure of oil flowing through it falls below a determined value due to the engine and thus the pump running temporarily at low speed, so as to give priority to the lubrication system at such times.

Abstract: A final drive assembly for an agricultural tractor has a casing in which are journalled the outer end of a half-shaft and, parallel to the half-shaft, a final drive shaft. The two shafts are driveably interconnected by fixed ratio speed reduction gearing lubricated by mineral oil contained in the casing. A multi-disc brake can frictionally interconnect the half-shaft and the casing, and is operated via a linkage by a hydraulic slave cylinder housed within the casing and preferably actuated by mineral oil to avoid contaminating the lubricating oil in the event of any leakage from the cylinder.

Abstract: Agricultural tractors having variable-track wheels for working in different conditions, particularly in row-crops, are known. The track-width of their driving wheels has sometimes been made power-adjustable by fixing brackets having respective grooves on the periphery of each hub and releasably clamping the brackets to respective helical rails fixed inside each rim and engaging the grooves. Due to the increasing size and power of tractors, and also to eventual wear of the components, it is difficult to achieve effective clamping. In an attempt to solve the problem, shims have been inserted where necessary between the brackets and the periphery of each hub. It is now proposed to solve the problem more positively by providing at least some of the brackets of each wheel with screws by which the brackets so provided can be adjusted in position radially of the hub before being fixed thereto.

Abstract: A power steering system for a wheeled agricultural tractor includes a pump circulating oil through a known steering-wheel-operated hydrostatic steering unit. A double-acting hydraulic cylinder communicates via conduits with the steering unit and is connectible to the tractor frame. A piston having a rod which projects from one end only of the cylinder is connectible to steer the tractor. A valve block interposed in the conduits causes oil displaced from the piston-rod end of the cylinder to flow to its other end when oil under pressure is supplied to said other end, and causes oil displaced from said other end to return directly to the steering unit when oil under pressure is supplied to the piston-rod end of the cylinder.

Abstract: An engine is combined with a dual clutch assembly comprising independently engageable and disengageable power take-off and drive clutches in tandem. To minimize the overall length of the combination despite the use of twin plates in the drive clutch, that face of the flywheel remote from the engine has a counterbore defined by a recessed driving surface and a surrounding axially-projecting flange, the power take-off clutch being disposed partially within this counterbore. Circumferentially-spaced radially-outwardly-projecting lugs on the pressure plate for the power take-off clutch are slideable axially in radial slots in the flange.

Abstract: Epicyclic gearing comprises a sun gear journalled on a shaft and meshing with a plurality of planet pinions which mesh also with a rotationally fixed annular gear, the pinions being journalled in a planet carrier having a floating driving connection with a sleeve rigidly secured on the shaft by splines and a lock-nut, the floating connection including respective sets of external gear teeth on the sleeve and the lock-nut and two sets of internal gear teeth on the planet carrier which mesh with the respective sets of external gear teeth, and the tip diameter of one set of teeth on the planet carrier being greater than the tip diameter of the teeth on the lock-nut.

Abstract: Adjustable mixed automatic height and draft control apparatus for a tractor power lift mechanism includes a height control rocker actuated by the tractor's rockshaft, a draft control rocker actuated by the tractor's hitch linkage, and a first balance lever moveable relative to either one of the rockers by movement of the other. A control linkage has its point of connection to the first balance lever variable by a first hand lever to adjust the mixture of height and draft control, a second hand lever gives over-riding manual control of the power lift mechanism, and a second balance lever is moveable relative to either one of the control linkage and the other hand lever by movement of the second. The second balance lever actuates the control valve of the power lift mechanism.

Abstract: A tractor has a power lift mechanism controllable automatically in known manner by implement draft load sensing apparatus. This apparatus comprises two leaf springs which are spaced apart in a lateral direction relative to the tractor, the springs being connected at their front ends to the tractor and being adapted to flex in the lateral direction but being stiff longitudinally of the tractor and vertically; two hitch links each connected to the rear end of one of the springs; and equipment for transmitting to the power lift mechanism a control signal derived from any variation in the distance between the flexible portions of the springs.

Abstract: A compression spring capable of having a very high rate comprises co-axial annular plates alternating in an axial direction with diametrical strips adjacent ones of which are perpendicular to one another. The spring may comprise a stack of washers with diametrically opposed pads or radial ribs on their faces, said washers having non-circular bores enabling them to be located non-rotatably on a correspondingly non-circular central support. Alternatively, the spring may comprise a single tubular element with pairs of diametrically opposed tangential slots perpendicular to its axis which extend from its periphery into its bore.

Abstract: Transfer gearing for converting a vehicle with a single power-driven axle to four-wheel-drive is housed partially within the vehicle's gearbox. The transfer gearing comprises a train of gears on vertically spaced shafts, the lowermost shaft having a coupling flange adapted to be driveably connected by a cardan shaft to an auxiliary power-driven axle, and the uppermost shaft being disengageably connectible by clutch means to the output shaft of the vehicle's gearbox. The clutch means comprise a dog clutch sleeve slideable axially by a selector fork operated manually by means including an arm pivotally mounted externally upon the vehicle's gearbox.

Abstract: A power take-off shaft assembly comprises a hollow drive shaft rotatable at one speed; a drive sleeve surrounding said shaft and rotatable simultaneously at another speed; a power take-off shaft with differently splined ends each adapted to fit within the drive shaft and with a central flange having an inner circle of equally spaced holes counterbored at one side of said flange and an outer circle of equally spaced holes counterbored at the other side thereof; and stepped bolts able to reach through said holes only from the counterbored ends thereof to secure the power take-off shaft to the drive shaft when fitted in said inner circle of holes whilst one end of the power take-off shaft projects operatively, and to secure the power take-off shaft to the sleeve when fitted in said outer circle of holes after turning said shaft end-for-end so that its other end projects operatively.

Abstract: An agricultural tractor has individually operable near-side and off-side brakes with respective brake levers. Said levers are disposed one at each side of a master lever, the three levers being pivotable about a common axis and each provided with a foot pedal. The master lever carries a pivotally mounted cross-bar arranged to operate both of the brake levers with an equalising action when the master lever is operated. One of the two brake levers is fixed to a transversely extending horizontal shaft journalled in a sleeve which is mounted on the tractor and rotatably supports a clutch-operating lever.

Abstract: A multi-cylinder 2-stroke fuel injection engine of the crankcase compression type has a separate crank chamber associated with each cylinder and inlet, transfer and exhaust ports in each cylinder. The exhaust ports of the engine communicate with an exhaust manifold which communicates with the turbine of an exhaust gas driven scavenge compressor, and the impeller of the compressor communicates with an inlet manifold which communicates with the inlet ports of the engine so as to pressure charge each crank chamber and thus increase the mass of air subsequently pumped to the associated cylinder by way of its transfer port.