Wheel tyre

The tyre pressure is also critical for conservation of the soil. With a lower tyre pressure, the area covered hy the tyre increases while at the same time the specific pressure exerted on the soil (kg/cm ) is reduced. As a general rule, tyres with as large a volume as possible should be chosen, so as to be able to keep the tyre pressure as low as possible (<1 bar), taking into account the minimum load-bearing capacity. The front wheel tyres of compact tractors, in particular, are usually too small, with the result that the area covered by the tyre is too small and excessive damage is done to the soil. 

This equation does, of course, assume that all the potential energy is converted into useful work. This is impossible in practice because some work will be done against friction - in wheel bearings, tyres and air resistance - and the free work must really be written as... 

In a pneumatic tyre, that portion of the structure which holds the tyre on the wheel it consists of a circular assembly of steel wires insulated with rubber, suitably wrapped and covered with rubberised fabric to enable the bead assembly to be built into the uncured casing. 

A shaped strip of mbber fitted between the beads of certain pneumatic tyre assemblies to protect the inner tube from damage by the beads and the wheel rim. 

An assembly of outer cover (or tyre) fitted with an inner tube and mounted on a metal rim or wheel, the inner tube is inflated with air under pressure which supports the load of the vehicle. In the tubeless tyre no separate inner tube is fitted, the outer cover itself being so constructed as to retain the inflation air. 

A tyre which is composed of solid rubber bonded to a suitable wheel and without an internal air space, as in the pneumatic tyre or an internal cavity as in the semi-solid tyre. The main uses of solid tyres are on forklift trucks and armoured fighting vehicles (tanks). 

Applied to a pneumatic tyre with no separate inner tube. An air-impermeable lining, usually of a halogenated butyl, is applied to the inside of the casing. The bead construction is such as to ensure an airtight lit on the wheel rim. Inflation is done through a valve fitted directly into a valve hole in the rim. 

In all tyres there are three types of components, the reinforcement layer(s), the rubber parts and the steel bead wires which locate a tyre to the wheel, or rim of a vehicle. Rubber is used in packing strips, inner lining, sidewalls and the abrasion-resistant tyre tread. 

Drum wheel test rigs are available to check the performance of tyres with retreads. 

In front of the building a timber floor protected by a eave should be laid. Trucks coming and going with materials should be moved by hand. Trucks with pneumatic-tyred wheels or barrows with bronze wheels are best for this purpose. If a narrow-gauged track is to be used, in the vicinity of buildings holding blackpowder, the rails should be of wood and the trucks should be fitted with bronze wheels. 

The Laboratory Abrasion Tester 100 (LAT 100)65 uses a wheel test piece on an abrasive disk geometry so is the type (d) of Figure 11.4. The abrasive disk is driven and the speed, contact force and the slip angle of the test piece can all be varied. What makes this apparatus so different from all the others is not only the versatility but the sophistication of the instrumentation and the computer control. This means that it can be used to obtain data as a function of several parameters and combine results to make predictions of wear for the extremely complicated service conditions of tyres. Not surprisingly, it is very expensive and unlikely to be used on a routine basis outside of tyre companies. Nevertheless, is has now been proposed for standardization in ISO TC 45. 

Determine whether car tires of different producers have different wear-out rates after 40.000 km. Mark the car tire types as A, B, C and D. The wear-out of car tyres will be tested on four types of cars. As each car needs four tyres, the experiment will test 16 tyres, four of each type. The experiment was done by each car having one type of each tyre. The sequence of putting tyres on wheels was completely random in order to center and eliminate the effect of differences between the wheels, if it exists at all. 

Boadicea was familiar with the use of iron, and the wheels of the early British war chariots were encircled with iron tyres, as is proved by remains found in Yorkshire, although it is very doubtful if they were fitted with scythes for laming hostile infantry, as was at one time believed. Undoubtedly many of the weapons wielded by Boadieea s troops against the Romans, a.d. 61, were also made with or strengthened by iron. 

Tires syn. tyres are the outer circumference of a wheel which makes contact with a surface. Metal tires are used on rail and other vehicles. Solid rubber tires are used in factories where they carry high loads to resist abrasion and puncture. Where the greatest need for protection from shock is required (e.g., in automobiles, aircraft, and other vehicles) pneumatic (compressed air-filled) tires are used. Tire assemblies consist of the tire and the wheel to which they are attached. Assemblies may also include rubber inner tubes which hold the air. On inflation, the edge of the tire is pressed against the rim of the wheel and forms an airtight seam or an inner tube is filled. Tires are manufactured to rated inflation pressures appropriate to the weight of the vehicle and driving conditions. 

Terminology used to describe tire and rim dimensions is explained in Figure 14.5. These dimensions are commonly used throughout the tire industry to describe size, growth, and wheel well clearance factors in addition to computation of variables such as load capacity and revolutions per unit distance traveled (The Tire Rim Association, Inc. Year Book, 2004 European Tyre and Rim Technical Organization, 2004). In addition, the following definitions should be noted ... 

The type, specification and main parameter of wheel and tyre see Table 4. 

Abnormal abrasion of tyre The front wheel alignment is badly Check the condition of front wheel... 

DMA is an analysis technique used to determine the dynamic properties of the elastomers [13, 14]. Dynamic properties of the elastomeric materials are important because they influence the performance of certain parts such as wheels and tyres. This method determines the storage modulus G (elastic behaviour), loss modulus G (energy dissipation), tan 8, loss compliance ]" and glass transition temperature (Tg) values. The Tg of the soft segment can determine the low temperature behaviour of polyurethane elastomers. This is not only influenced by the nature of the soft... 

Loss compliance quantifies the heat generated during dynamic loading in applications like tyres, wheels and rollers. Polyurethane elastomers with lower loss compliance values will experience less heat build up and, consequently, may suffer fewer field failures [14]. Figure 8.8 shows the graph of loss compliance as a function of temperature for the cast elastomers made with HER extended materials. The results are summarised in Table 8.5. 

Kinetic energy Noncontainment of moving components (e.g. RAT, Fans, APU Engine, burst pressure vessel). Wheels (e.g. tyre burst, flaiUng tread, lim release, etc). FlaUing shafts. Need to consider issues such debris trajectory (e.g. see ARP4761, p. 304) and resulting vibration, loss of function, etc. 

The polishing machine (see Figure 2.5) has a metal wheel called the road wheel. This is 406 mm in diameter and holds the test specimens and the stone control specimens around its rim. The number of specimens placed around the wheel is 14 in total. The wheel rotates at 320 revolutions per minute during the test. The rubber-tyred wheel has a static contact force with the moulds of 725 N. For the first 3 h of the test, corn emery is fed onto the wheel at a rate of 27 7 g/min together with a sufficient amount of water. The corn emery has a gradation with 98%-100% of the particles passing through the 0.600 mm sieve. 

---