Spiral Escalator at Holloway Road Station

Fig. 8 from Astin's 1902 patent specification

1906. From 'The Engineer'

In 1906 a spiral escalator was installed in a vertical shaft at the Holloway Road Station on the Great Northern, Piccadilly and Brompton Railway. On paper, it offered an attractive alternative to lifts, stairs, or the less compact conventional (but still relatively novel) escalators. It was installed on an experimental basis by its manufacturer, at no cost to the railway company. A larger version had been installed for amusement purposes at Earls Court.

1906: From 'The Engineer': 'At Holloway Station, besides the lifts, there is a passenger conveyor - Fig. 3. This apparatus has been installed experimentally by the Reno Electric Stairways and Conveyors Limited, London. It consists of a double· spiral continuously-moving track occupying one of the lift shafts, and passengers can travel in both directions simultaneously. At the top and at the bottom the moving gangway passes for a short distance under the flooring. The speed is 100ft. per minute. The moving surface consists of wrought steel chains bridged with teak slats, and it is guided up and down the shaft by wheels running on a spiral track. A flexible handrail moving at the same speed as the conveyor is provided, and both are driven by sprocket wheels meshing into the links of the chains. ....'

The Holloway example never went into public service, and it was removed in 1911.

In 1988 the remains of the lower part of the escalator were discovered at the bottom of the shaft. They were later recovered and removed to London Transport Museum's Acton Depot.

Most sources credit Jesse Wilford Reno with its design. However, it is not clear that he had any direct involvement in the project. The spiral escalator was designed and built by the London-based company Reno Electric Stairways and Conveyors, formed in 1902 after reaching an agreement with the Reno Inclined Elevator Co and Jesse Wilford Reno to buy the relevant Reno patents. William Henry Aston, a British engineer and inventor, was Managing Director of that company. He was also a partner in G. Aston and Son, who in 1900 had built the first British installation of the 'inclined elevators' patented by J. W. Reno. This involvement evidently inspired William Henry Aston to seek further development of the principle, and in 1901 he patented the spiral escalator.

Aston's patent included the description 'Supporting or protective framework or housings for endless load-carriers or traction elements of belt or chain conveyors for conveyors having endless load-carriers movable in curved paths in three-dimensionally curved paths'. It was also patented in the USA - see US Patent No. 701,459, dated June 3, 1902

See here and here for fascinating accounts of Reno's elevators, and of the spiral elevator or escalator which was installed at London's Holloway Road underground station (but never used). The latter source states that the device should be described as an elevator rather than an escalator. The 'scala' part of the name means 'steps' in Latin.

Good photos here showing remains of the escalator preserved at the London Transport Acton Depot.

The spiral escalator mainly differed from the familiar continuous escalator by taking a spiral (helical) path, which allowed for a compact installation compared with a conventional escalator. Also, unlike typical escalators, the treads were not stepped.

The key features of the escalator were probably as follows:-

The basic structual feature was a spiral angle-iron track guiding the moving articulated platform. The track would support and guide the continuously-moving platform thoughout its ascent and descent.

Aston's 1901 patent proposed two possible arrangements, one having the rising track immediately above or below the descending track, and the other having the descending track located within the ascending track (i.e. at a smaller radius). The latter arrangement (see illustration) was adopted at Holloway Road Station. The connection between the two helixes was a short horizontal section. It appears that the horizontal sections were not utilised for passenger access.

The moving track comprised a series of small wheeled platforms interconnected by a continous chain. In this respect the track resembled the familiar escalator, except that the platforms were not stepped and, critically, they had to negotiate a path having variable curvature. The platforms, or treads, were slightly tapered (when viewed from above). The clearance between them must have been sufficient to accommodate the track's changes in radius. The treads were driven by a continuous chain whose links were pivoted so as to allow flexure in the horizontal and vertical planes. It can perhaps be envisaged as a series of Hooke's joints.

Aston's patent drawings show each tread having a small wheel at each end, and a smaller lateral wheel at the inboard end, to reduce friction against the guide rail. In fact, photos in the above links show a better arrangement, with three small wheels supporting each tread, and, instead of the lateral wheel on the end of the tread, there was a large central roller which was part of the chain. This roller ran within angle-iron guides, supported from the main guide rails by cast iron brackets. See photo above.

It is evident that lubrication and wear of the small wheels and axles would have been a potential source of trouble.

It is not difficult to see that serious concerns would have been voiced over passenger safety. Some of the above links include a photograph taken during construction, and this shows the steepness of the inclination. The 1906 'Engineer' article stated that 'A flexible handrail moving at the same speed as the conveyor is provided. This presumably had its own driving chain, and it would be interesting to know more about the arrangement. In the case of the earlier machine at Earl's Court (a fairground ride called 'A Climb in the Pyrenees') one fixed and one moving handrail were provided.

The treads were provided with cleats to aid grip. These were probably rubber or wooden pads set in a cast metal matrix.

The treads were narrow, and the adjacent spiral corridor was presumably narrow, too. Even if the mechanism was not operating, the consequences of passengers pushing and panicking in the crowded space would be intolerable.

See Also

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