Spiral Escalator at Holloway Road Station

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

The Holloway example never went into public serice, 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 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 escalator was designed and built by the Reno Electric Stairways and Conveyors. William Henry Aston, a British engineer and inventor, was Managing Director of that company, and he had patented the spiral escalator in 1901. In 1901 the company had reached an agreement with the Reno Inclined Elevator Co and Jesse Wilford Reno to buy the relevant Reno patents.

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 spiral elevator was patented by William Henry Aston and constructed by Reno Electric Stairways and Conveyors Ltd, of which Aston was a Director.

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

The spiral escalator was a form of the familar continuous escalator taking a spiral (helical) path, which allowed for a compact installation compared with a conventional escalator. 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 was adopted at Holloway Road. To connection between the two helixes was a short horizontal section. This is where the plucky travellers would step on and off.

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.

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. This would have been particularly alarming given the apparent absence of moving handrails. There is nothing to suggest that moving handrails were provided. These would have required their own complicated mechanism.

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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