Protofour or P4 is a set of standards for model railways allowing construction of models to a scale of 4 mm to 300 mm (1 ft) (1:76.2),[1] the predominant scale of model railways of the British prototype. For historical reasons almost all manufacturers of British prototype models use 00 gauge (1:76.2 models running on 16.5 mm (0.65 in) gauge track). There are several finescale standards which have been developed to enable more accurate models than 00, and P4 is the most accurate in common use.
The P4 standards specify a scale model track gauge of 18.83 mm (0.741 in) for standard gauge railways. Joe Brook Smith was the first to propose use of an exact scale track gauge in July 1964, when also the term “Protofour” was invented by Malcolm Cross.[2] The standards were later published in Model Railway News by the Model Railway Study Group in August 1966.
Just as in the prototype railway, on a model the wheel-rail interface is the fundamental aspect of reliable operation. So as well as a track gauge, P4 also specifies the wheel profile and track parameters to use, which are largely a scaled-down version of real-life standards with some allowances for practical manufacturing tolerances.
P4 standards have been extended to several other prototypes. Broader than standard gauges have been modelled using P4 standards, including Brunel's7 ft 1⁄4 in (2,140 mm) gauge, modelled with 28.08 mm (1.106 in) track[3]: 2 [4] and Irish P4, the 5 ft 3 in (1,600 mm) Irish broad gauge modelled in P4 in 4 mm scale with 21 mm (0.827 in) gauge track.[3]: 2 [5] Several successful models of narrow gauge prototypes with a correspondingly accurate track gauges have also been produced to P4 standards.
P4 standards are promoted worldwide by the Scalefour Society, which is based in the United Kingdom. The EM Gauge Society also provides support for modelling to P4 standards: many P4 modellers belong to both societies. The standards document is hosted by the Scalefour Society[3] and the society's Central London Area Group (CLAG) make a HTML version available.[6]
S4 Standardedit
The S4 Standard is maintained as part of the P4 standards.[3]: 4 The S4 Standard removes an allowance in the P4 standards for the tight (compared to the prototype) curves used on model railways. The wheel back to back in S4 is therefore slightly wider than P4, and the related track work dimensions are dead-scale.
Scalefour Society, supporting modelling to P4 standards
EM Gauge Society, supporting modelling to both EM and P4 standards
CLAG - a group of finescale modellers based around London, England interested in building visually accurate working scale models in 4 mm scale 18.83 mm (0.741 in) gauge
^Scalefour Society Digest 1.2, 'P4 Track and Wheel Standards' (Issue 2.4), HTML
April 18, 2024
protofour, standards, model, railways, allowing, construction, models, scale, predominant, scale, model, railways, british, prototype, historical, reasons, almost, manufacturers, british, prototype, models, gauge, models, running, gauge, track, there, several,. Protofour or P4 is a set of standards for model railways allowing construction of models to a scale of 4 mm to 300 mm 1 ft 1 76 2 1 the predominant scale of model railways of the British prototype For historical reasons almost all manufacturers of British prototype models use 00 gauge 1 76 2 models running on 16 5 mm 0 65 in gauge track There are several finescale standards which have been developed to enable more accurate models than 00 and P4 is the most accurate in common use P4Scale4 mm to 1 ft 305 mm Scale ratio1 76 2Model gauge18 83 mm 0 741 in Prototype gaugeStandard gaugeWebsiteScalefour SocietyThe P4 standards specify a scale model track gauge of 18 83 mm 0 741 in for standard gauge railways Joe Brook Smith was the first to propose use of an exact scale track gauge in July 1964 when also the term Protofour was invented by Malcolm Cross 2 The standards were later published in Model Railway News by the Model Railway Study Group in August 1966 Just as in the prototype railway on a model the wheel rail interface is the fundamental aspect of reliable operation So as well as a track gauge P4 also specifies the wheel profile and track parameters to use which are largely a scaled down version of real life standards with some allowances for practical manufacturing tolerances P4 standards have been extended to several other prototypes Broader than standard gauges have been modelled using P4 standards including Brunel s 7 ft 1 4 in 2 140 mm gauge modelled with 28 08 mm 1 106 in track 3 2 4 and Irish P4 the 5 ft 3 in 1 600 mm Irish broad gauge modelled in P4 in 4 mm scale with 21 mm 0 827 in gauge track 3 2 5 Several successful models of narrow gauge prototypes with a correspondingly accurate track gauges have also been produced to P4 standards P4 standards are promoted worldwide by the Scalefour Society which is based in the United Kingdom The EM Gauge Society also provides support for modelling to P4 standards many P4 modellers belong to both societies The standards document is hosted by the Scalefour Society 3 and the society s Central London Area Group CLAG make a HTML version available 6 S4 Standard editThe S4 Standard is maintained as part of the P4 standards 3 4 The S4 Standard removes an allowance in the P4 standards for the tight compared to the prototype curves used on model railways The wheel back to back in S4 is therefore slightly wider than P4 and the related track work dimensions are dead scale See also editOO gauge EM gauge Finescale Standards Rail transport modelling scalesExternal links editScalefour Society supporting modelling to P4 standards EM Gauge Society supporting modelling to both EM and P4 standards CLAG a group of finescale modellers based around London England interested in building visually accurate working scale models in 4 mm scale 18 83 mm 0 741 in gaugeReferences edit Overview of the P4 Standards Protofour Chronology a b c d Scalefour Society Digest 1 2 P4 Track and Wheel Standards Issue 2 4 BGS Standards Broad Gauge Society Retrieved 2021 05 11 Steve Johnson s Irish P4 Models Scalefour Society Digest 1 2 P4 Track and Wheel Standards Issue 2 4 HTML Retrieved from https en wikipedia org w index php title Protofour amp oldid 1151917279, wikipedia, wiki, book, books, library,
