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26-555: The Deeside Tramway was a gravity and horse-worked, 2 ft 6 in ( 762 mm ) narrow gauge industrial railway connecting the slate workings on the Dee valley with the main road at Glyndyfrdwy and later the Great Western Railway 's Ruabon - Dolgellau railway. It was one of the last tramways in regular use to use wooden rails covered in iron sheaths. The tramway was constructed around 1870, following

52-518: A normal distribution , the tails of measured values may extend well beyond plus and minus three standard deviations from the process average. Appreciable portions of one (or both) tails might extend beyond the specified tolerance. The process capability of systems, materials, and products needs to be compatible with the specified engineering tolerances. Process controls must be in place and an effective quality management system , such as Total Quality Management , needs to keep actual production within

78-529: A clearance fit of somewhere between 0.04 mm (largest shaft paired with the smallest hole, called the Maximum Material Condition - MMC) and 0.112 mm (smallest shaft paired with the largest hole, Least Material Condition - LMC). In this case the size of the tolerance range for both the shaft and hole is chosen to be the same (0.036 mm), meaning that both components have the same International Tolerance grade but this need not be

104-460: A number. For example: H7 (hole, tapped hole , or nut ) and h7 (shaft or bolt). H7/h6 is a very common standard tolerance which gives a tight fit. The tolerances work in such a way that for a hole H7 means that the hole should be made slightly larger than the base dimension (in this case for an ISO fit 10+0.015−0, meaning that it may be up to 0.015 mm larger than the base dimension, and 0 mm smaller). The actual amount bigger/smaller depends on

130-426: A shaft with a nominal diameter of 10   mm is to have a sliding fit within a hole, the shaft might be specified with a tolerance range from 9.964 to 10 mm (i.e., a zero fundamental deviation, but a lower deviation of 0.036 mm) and the hole might be specified with a tolerance range from 10.04 mm to 10.076 mm (0.04 mm fundamental deviation and 0.076 mm upper deviation). This would provide

156-403: A specified temperature range, over a specified lifetime, and so on. Many commercially available resistors and capacitors of standard types, and some small inductors , are often marked with coloured bands to indicate their value and the tolerance. High-precision components of non-standard values may have numerical information printed on them. Low tolerance means only a small deviation from

182-442: Is also extremely useful: It indicates the frequency (or probability) of parts properly fitting together. An electrical specification might call for a resistor with a nominal value of 100 Ω ( ohms ), but will also state a tolerance such as "±1%". This means that any resistor with a value in the range 99–101   Ω is acceptable. For critical components, one might specify that the actual resistance must remain within tolerance within

208-409: Is analogous to "goal posts" in a football game : It implies that all data within those tolerances are equally acceptable. The alternative is that the best product has a measurement which is precisely on target. There is an increasing loss which is a function of the deviation or variability from the target value of any design parameter. The greater the deviation from target, the greater is the loss. This

234-617: Is described as the Taguchi loss function or quality loss function , and it is the key principle of an alternative system called inertial tolerancing . Research and development work conducted by M. Pillet and colleagues at the Savoy University has resulted in industry-specific adoption. Recently the publishing of the French standard NFX 04-008 has allowed further consideration by the manufacturing community. Dimensional tolerance

260-441: Is not a usable part according to the design intent. Tolerances can be applied to any dimension. The commonly used terms are: This is identical to the upper deviation for shafts and the lower deviation for holes. If the fundamental deviation is greater than zero, the bolt will always be smaller than the basic size and he hole will always be wider. Fundamental deviation is a form of allowance , rather than tolerance. For example, if

286-422: Is related to, but different from fit in mechanical engineering, which is a designed-in clearance or interference between two parts. Tolerances are assigned to parts for manufacturing purposes, as boundaries for acceptable build. No machine can hold dimensions precisely to the nominal value, so there must be acceptable degrees of variation. If a part is manufactured, but has dimensions that are out of tolerance, it

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312-552: The Moel Fferna quarry . These extensions were laid with traditional iron rails, although the original section retained the wooden rails throughout its lifetime. The line continued operating until just after the end of the Second World War , finally closing in 1947. Throughout its life the tramway was operated by gravity workings from the quarries to Glyndyfrdwy , with return trains hauled by horses. The remains of

338-601: The base dimension. For a shaft of the same size, h6 would mean 10+0−0.009, which means the shaft may be as small as 0.009 mm smaller than the base dimension and 0 mm larger. This method of standard tolerances is also known as Limits and Fits and can be found in ISO 286-1:2010 (Link to ISO catalog) . The table below summarises the International Tolerance (IT) grades and the general applications of these grades: An analysis of fit by statistical interference

364-424: The case in general. When no other tolerances are provided, the machining industry uses the following standard tolerances : When designing mechanical components, a system of standardized tolerances called International Tolerance grades are often used. The standard (size) tolerances are divided into two categories: hole and shaft. They are labelled with a letter (capitals for holes and lowercase for shafts) and

390-403: The components given value, when new, under normal operating conditions and at room temperature. Higher tolerance means the component will have a wider range of possible values. The terms are often confused but sometimes a difference is maintained. See Allowance (engineering) § Confounding of the engineering concepts of allowance and tolerance . In civil engineering , clearance refers to

416-404: The damp cuttings. Occasionally, a line of rusty metal marks where one of the tie bars that held the rails to gauge sat. In at least one location, a metal rail sheath is still visible over the wood of a rail. Above Nant-y-Pandy the route passes the site of the reservoir that provided water power to the mill's overshot waterwheel, before the formation is breached by the valley road. Above Ty'n y Wern

442-653: The desired tolerances. A process capability index is used to indicate the relationship between tolerances and actual measured production. The choice of tolerances is also affected by the intended statistical sampling plan and its characteristics such as the Acceptable Quality Level. This relates to the question of whether tolerances must be extremely rigid (high confidence in 100% conformance) or whether some small percentage of being out-of-tolerance may sometimes be acceptable. Genichi Taguchi and others have suggested that traditional two-sided tolerancing

468-401: The difference between the loading gauge and the structure gauge in the case of railroad cars or trams , or the difference between the size of any vehicle and the width/height of doors, the width/height of an overpass or the diameter of a tunnel as well as the air draft under a bridge , the width of a lock or diameter of a tunnel in the case of watercraft . In addition there is

494-564: The early 1960s At the top of the incline the walls of the winding house still stand. From here a footpath follows the trackbed of the tramway. There are occasional sleepers and lengths of flat-bottomed rail along this section. There are several building remains at the Deeside Slate Works and explanatory signboards have been installed there. Running south is the shallow incline towards Deeside Slab Quarry . There are longitudinal wooden rails still in situ in many places, especially in

520-438: The effects of tolerances: Design of experiments , formal engineering evaluations, etc. A good set of engineering tolerances in a specification , by itself, does not imply that compliance with those tolerances will be achieved. Actual production of any product (or operation of any system) involves some inherent variation of input and output. Measurement error and statistical uncertainty are also present in all measurements. With

546-603: The opening of the Llangollen and Corwen Railway which passed through Glyndyfrdwy. The tramway initially ran from the Deeside Slate Works at Nant-y-Pandy to the Deeside quarry. The tramway was unusual in its use of wooden rails with iron sheaths on the running surfaces, a very early form of permanent way, and one that had almost entirely died out by this date. In the late 1870s the tramway was extended in two directions to bring its total length to 3 miles (4.8 km). The line

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572-423: The tolerance (for example, a temperature that is too hot or too cold) is said to be noncompliant, rejected, or exceeding the tolerance. A primary concern is to determine how wide the tolerances may be without affecting other factors or the outcome of a process. This can be by the use of scientific principles, engineering knowledge, and professional experience. Experimental investigation is very useful to investigate

598-636: The tramway formation reappears on the hillside above the road, past Tan-y-Graig, until the road climbs up and takes over the tramway route. From here until the Deeside quarry, the tramway formation is now a farm road. The formation crosses the head of the valley in a horseshoe curve and rounds the bluff to reach the quarry. At the south-west edge of the quarry an incline leads up to the route to Moel Fferna quarry . 2 ft 6 in gauge railways 2 ft 6 in ( 762 mm ) gauge railways are narrow gauge railways with track gauge of 2 ft 6 in ( 762 mm ). This type of rail

624-522: The trans-shipment wharf are on the east of the crossing keeper's box on the Llangollen Railway and are now part of a children's play area. The inclined plane runs approximately south up the hill. One modern house is built across the incline on the north side of the A5 road. Another house has been built across the formation on the south side of the A5, and the tunnel under the road was filled-in during

650-465: Was extended north from the Deeside slate works along the east side of Nant-y-Pandy to the head of a long incline that dropped through Glyndyfrdwy to a transhipment wharf with the Llangollen and Corwen Railway. The line was extended south and west from Deeside Quarry, running up the west side of the quarry by a further incline, then looping westwards along the hillside to the foot of the exit incline of

676-642: Was promoted especially in the colonies of the British Empire during the second half of the nineteenth century by Thomas Hall and Everard Calthrop . Several Bosnian-gauge railways with 760 mm ( 2 ft  5 + 15 ⁄ 16  in ) are found in south-eastern Europe. 760 mm (29.92 in) is well within tolerances of 762 mm (30.00 in). Engineering tolerance Dimensions, properties, or conditions may have some variation without significantly affecting functioning of systems, machines, structures, etc. A variation beyond

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