Automotive Technical Terms: Labyrinth Seal to Lucar Connector
Throughout this site we use many technical terms, and given the breadth of readership our site enjoys, sometimes we are remiss and incorrectly assume everyone knows what we are referring to. For those that do not, here are some explanations of the technical terms use.
A design of seal for a rotating shaft in which the pressure differential from one side to the other is broken down into sufficiently small increments across each of the multi-stages of the seal so that leakage is negligible. It usually consists of a series of alternating filaments resembling closely fitting washers, one set attached to the shaft and the alternating members attached to the housing, with very fine clearances between.
Valve lag is the degree of crankshaft rotation after TDC, for the exhaust valve or after BDC, for the inlet valve, to the point where the valve closes, this interval depending on design and speeds, making use of the gas inertia to achieve volumetric efficiency.
The smooth passage of a gas or liquid past a body without turbulence, each particle flowing in smooth lines. This is only achieved if the body is perfectly streamlined.
A windscreen that is fabricated from two or more layers of glass joined by a clear plastic layer, which is more resistant to impact by flying stones than a conventional windscreen.
The heat required to change the state of a material from solid to liquid or liquid to vapour or the heat given out in the reverse of these processes, no change in temperature being caused.
A patent flexible joint, used as an alternative to the more conventional Universal or Hookes joint, which obtains resilience for angular deflections up to approximately 15� by the elastic deformation of rubber bushes set in a metal cage between the spiders of the two shaft ends.
The dissolving of some ingredient in a material, its loss changing the properties of the substance. This occurs naturally with some leather cloths and plastics in the atmosphere, especially in sunlight, resulting in brittleness and change of texture.
The normal car battery consisting of cells with positive plates which are lead grids impregnated with lead peroxide, alternating with negative plates bearing spongy lead, insulated from each other by porous non-conductors and immersed in an electrolyte of diluted sulphuric acid. Each cell normally produces two volts and is connected in series with other cells to provide 12 volts for the usual car battery.
Valve lead is the crankshaft angle before TDC for the inlet valve (before BDC for exhaust valve) at which the valve commences to open, this anticipation enhancing gas flow (see Lag).
The process of applying semi-molten solder over a joint or weld of steel panels or over distorted or corroded areas, to permit restoration of the contour and surface finish before painting.
The brake shoe in a drum brake which gains some servo force from the rotation of the drum, increasing the braking effect. In the direction of rotation, its operating end "leads" and the pivoted end "trails". On rear wheel brakes there is one trailing shoe and one leading shoe to give adequate braking in both directions, especially when the handbrake is used. Front wheel drum brakes, with few notable exceptions, have twin leading shoes to give maximum effect in forward motion.
A spring consisting of a single leaf or, more commonly, a series of metal strips which are assembled one on top of another, each strip being shorter than the one above it. The strips are clamped together and both ends of the resulting spring are attached to the vehicle's chassis. The axle is attached to the spring which absorbs shocks imparted by variations in the road surface by flexing. Leaf springs may be mounted longitudinally or transversely.
An inadvertent ingress of air into the induction manifold due to gasket failure or loose unions resulting in weak mixture, overheating and irregular tick-over.
A lean (or weak) mixture has excess air compared with the chemically correct or normally accepted mixture strength. This can result in loss of power, flat spots during acceleration and overheating possibly causing damage to the spark plugs, exhaust valves and even the piston crowns.
The facility on certain hydraulic suspension systems to compensate for variations in the loadings on the rear axle and maintain the normal level of the vehicle.
Conventional rear axle set-up that contains rotating drive shafts. The actual term 'live' refers to the fact that the axle transmits power as opposed to a dead axle whose sole function is suspension.
Electrical cables collected together in an outer sheath with individual cables diverging at points appropriate to the installation in the vehicle or assembly, the cables being coloured for identification.
Distortion of a chassis or body shell due to offset collision, resulting in transverse stations or members (such as axle lines) being set other than normal to the longitudinal line of the vehicle.
The minimizing of friction between solid surfaces in sliding or rolling contact, by provision of some liquid (usually an oil) or grease as an intermediary, which reduces the wear and frictional heat generated. For bearings under heavy loading oil may be constantly applied under pressure, whereas in other cases a film of oil is sufficient.
A snap type electrical connection between a cable and a terminal on a component or between two cables, the terminal (or male end) being a plated flat strip and the mating item being a metal sheath to slide over the terminal, the whole being insulated.
