There is sometimes as much engineering skill in the designing and building of the “rides” in an amusement park as there is in a new bridge. The safety of thousands of holiday-makers depends on the careful and accurate planning of the engineer
MORE THAN TWO HUNDRED FEET ABOVE THE GROUND the cars of the “Sky Ride” travelled above the Century of Progress Exhibition at Chicago, U.S.A., in 1933. Each of the twelve cars held thirty-two persons and was suspended from an eight-wheeled trolley. The four outer wheels acted as supports and the inner wheels were specially grooved to clutch the rope. The speed of the cars was about six miles an hour. In five months, 3,000,000 passengers made the trip without mishap.
INNUMERABLE are the ways in which engineering has improved the amenities of modern life, in large things and in small, in important things and in unimportant. No one can say that he does not derive enjoyment today from things which are in reality the product of engineering skill. The cinema and the radio are two forms of entertainment which have not long been in existence but are now available to all. The theatre, the earliest form of entertainment, has benefited on the technical side by the mechanical aids that the engineer has evolved. An excellent example of the work of the engineer in improving our amusements is afforded by the special hydraulic lift installed (as described in the chapter “Lifts and Escalators”) for the convenience of dancers and diners in a London hotel. In the amusement parks and fun fairs, now so popular, engineering is not the least important feature. There is sometimes as much engineering skill put into designing and building a roundabout as into a new bridge.
To many thousands of people the modern fun fair stands for an escape from the boredom of a workaday existence, where the thrills and excitement so lacking in everyday life may be obtained, although in an artificial way.
To cater for these thousands, great permanent amusement parks have sprung up all over the world. Clever engineers have applied their training and skill to the devising of new “rides”.
The progenitor of the modern machines was the, little merry-go-round. It seems quite childish now, but at one time it gave people a thrill. A few of these machines that have not been sent to the scrap heap have been acquired by museums. From these small, often hand-driven machines were developed large roundabouts with a diameter of 60 feet or more, resplendent in gold leaf and glass jewels, costing upwards of £7,000. There was not always one central motor. Often each car had its own. The merry-go-round has passed through technical stages of man power, animal traction, steam, petrol and electricity.
At the earlier Earls Court Exhibitions the Big Wheel, whose gigantic silhouette loomed long over London, was the centre of attraction. Apart from the thrill of the aerial orbit, there was, at the top, a fine view over the City on a clear day. The wheel was copied from the Ferris Wheel of America — a device which is still in use. The machinery was not infallible and on several occasions it broke down, leaving passengers marooned in the glass cages far above the ground. The proprietors astutely transformed this disadvantage into a good “draw” by offering £10 compensation to all sufferers from a mechanical breakdown. A similar but smaller wheel was a great attraction at the Paris Exhibition of 1900. In 1908, the sensation of the Franco-British Exhibition at the White City, London, was the “Flip Flap”. This had two long arms which moved in a semicircle. At the end of either arm was a cage. In the same way as the Big Wheel, the machinery was not infallible and there were times when the arms became stuck half-way.
A study of the switchback, or scenic railway, gives a good idea of developments made in the design of machinery for amusement parks. The first to be built in Europe was the Blackpool Scenic Railway, in 1907, recently been demolished to make way for a new one, the largest and fastest in Europe. The highest point of the new track is 72 feet above the ground. In the old railway it was 40 feet. The new railway attains a speed of 72 miles an hour in places; on one section a distance of three-quarters of a mile is covered in one and a half minutes. On the old railway the greatest speed was between 30 and 35 miles an hour.
On the Blackpool railway there are six trains in service, each consisting of three cars carrying eighteen passengers. Each car has twelve wheels. Two trains run on separate tracks simultaneously.
The materials used in building railway included 500,000 feet pitch pine weighing 2,000,000 lb., 139 tons of steel, five tons of nails, 20,000 screws and 25,000 bolts. Of the 139 tons of steel, seventy-nine tons were used on the station and sixty tons on the track and various other fittings. The cars, linked by universal spring couplings, weigh five tons fully loaded. Each successive railway has been made longer and steeper, so that recently, as on the Blackpool Scenic Railway, it has been found necessary to provide chain traction to pull the trains up to the starting point. From the loading platform the track is graded down to the base of the pull-up, or inclined hoist, so that immediately the train is released it travels down to the pull-up on its own momentum. The grade is designed so that when the train reaches the pull-up it is travelling at the same speed as the hoisting cable, to which it is then coupled by cogs under the cars.
On the pull-ups safety ratchets are provided, so that in the unlikely event of the motor stopping or the chain breaking the cars cannot run back. Electric motors of 125 horse-power are used for hauling. On some scenic railways, for additional safety, the cars are equipped with automatic optical signalling plant which is electro-magnetically actuated by the cars. Collisions are thus virtually eliminated.
The Switchback and Dipper are gravity rides of the type commonly known as coasters. The three coasters in Blackpool are the Roller Coaster, the Big Dipper and the Grand National.
Coasters can be built to give either the thrills of a fast ride, with not excessive drops, or a slightly slower ride, the sensation being given by the steepness of the dips. The Roller Coaster is a mild type of ride with not excessively steep drops and a fast run into the station down a series of mild dips.
THE BIG WHEEL dominated the Earl’s Court Exhibitions in London before the war of 1914—18. There were forty cars suspended at the circumference of the great steel structure. The complete orbit was traversed in twenty minutes and power was supplied by two electric motors 50 horse-power. The design was based on that of an American wheel.
The Big Dipper, as its name suggests, provides its thrills by the steepness of the drops. The Grand National is what is termed a racing coaster and has a double track running over a figure-of-eight course. The two trains, one on either track, leave the station simultaneously and are carried to the top of the pull-up together. Having left the chain at the top of the pull-up, the trains pass and repass each other according to whether they are on the inside or outside of the curves on the track. In addition to the sensation given by the steepness of the drops and the high speed of the ride, there is the additional thrill of racing.
One Big Dipper has 3,000 feet of track and the top of the pull-up is 65 feet above ground level. Another similar railway has 3,500 feet of track and a pull-up height of 72 feet. The tracks are carried on trestles 9 feet apart, some of which are over 60 feet high. The wood used is pitch pine, chemically treated with zinc chloride, which to some extent makes the timber fire-resisting, though not fireproof.
At one point the railway at Blackpool is carried across a road on a pitch pine truss with a span of 140 feet. One switchback includes five almost sheer drops of over 50 feet.
There are not many designers and inventors of amusement apparatus in Great Britain. A great number of rides are made from American designs, and the Continent is eagerly scoured for any novelties. The design and manufacture are carried on by skilled engineers in much the same way as any other machinery. About two thousand people are engaged in the trade in Great Britain, and most of the apparatus is made there, the principal exceptions being chiefly the larger portable gravity rides, which generally come from Germany. The Flying Boats are another form of roundabout. In one machine the boats are raised by a 15 horse-power motor to about 40 feet above the ground. The horizontal rotation is then effected by a 26 horse-power motor suitably geared down with worm gearing. In another type, a miniature aeroplane at the end of a horizontally revolving arm is driven round by its own airscrew and controlled to a large extent by its passengers. Another large roundabout has twelve boats in the form of planes, each with a permissible load of 1,100 lb.
Swung Round a Hairpin Bend
These boats are not drawn up, but hang on wire cables about 50 feet long, so that when a 25 horse-power motor swings them round, they fly outwards by centrifugal force and describe a circle with a periphery of about 140 feet.
In another kind of “merry-go-round” there are about twenty cars, each holding two or more persons. These cars are driven through radial arms round a circular railway, often switch-backed, by a 14½ horse-power motor. The “Whip” has semicircular cars in which two or three passengers sit facing the direction of travel. The cars run on castors on a steel track in a rectangular building. The track consists of two parallel straight portions running the length of the building and joined at either end by a semicircular portion of track. The cars are attached by radial arms to a steel cable, propelled by two large-diameter moving wheels fitted horizontally to the track at either end of the building. The effect is that the cars are pulled along the straight sides of the track by the cable, and when they reach the revolving wheel at either end of the track the tendency is for the car to fly out as it is pulled round the abrupt hairpin bend.
THE SKY RIDE at the Chicago Exhibition of 1933 was essentially a transporter bridge with two towers, 628 feet high and 1,850 feet apart. At an elevation of about 234 feet a track cable system supported twelve cars, in which passengers travelled across part of Lake Michigan. Each tower had a base 110 feet square. Four lifts in each tower conveyed passengers to the cars, and two lifts served the observatory at the top.
This tendency for the car to fly out at a tangent is increased by the steel track being sloped away from the radius of the revolving wheel. The radial arms by which the cars are attached to the moving cable have built into them a strong spring which allows the cars a small amount of outward play as they are swung round the hairpin bend. The general effect is that the cars are whipped round at either end of the building and then are pulled gently along the straight side of the track until they come to the bend at the other end.
The “Reel” is a ride on which the cars run down a track built on an inclined plane. The track consists of a series of straights and hairpin bends gradually becoming steeper as the cars run lower down the plane. The car itself is completely circular and the passengers sit in it facing inwards. The cars are carried to the top of the ride by a pull-up similar to that of a coaster. From the top of the pull-up the car runs down a slight slope until it comes to a hairpin bend. It then proceeds along a further straight slope immediately below the previous one, but at a lower level. It continues down this series of straights and hairpin bends, the straight portions of the track becoming less and less as it gets lower down the incline until the last bend becomes a complete semicircular swoop round, and the car finally runs into a straight, where it loses its momentum and comes to rest in the station.
A device depending on centrifugal force is the “Joy Wheel”, a horizontal wheel regulated up to 35 revolutions a minute by a controller which alters the field resistance of an 8½ horse-power motor. Persons on the wheel try to prevent themselves from being thrown off the wheel by centrifugal force.
Among the most popular rides of recent years are the noisy “Auto Skooters”, with their terrific bumping and head-on collisions. At one park, there were twenty-four cars driven by motors of ¾ horse-power at 1,750 revolutions a minute. The current came from large transformers which stepped down from 460 volts to 115 volts. At times the load is tremendous, particularly when there is a jam. At Blackpool as many as thirty-six cars are on the track at the same time. The cars have pressed steel bodies, similar to those of many motor cars, and are mounted on timber bases which give a certain resilience to withstand the severe bumping they suffer.
The electric boats work on a similar principle. One pool, 180 feet long, has thirty boats, each containing an electric motor of 6| horse-power and running at 1,200 revolutions a minute, fitted in the same way as an inboard petrol motor for small boats. A forward or reverse movement is effected simply by giving the steering wheel one complete turn. The boats, which travel at about six miles an hour, cannot capsize. Contrary to past practice, the power does not come from overhead wire netting earthed to the water. The process is reversed. The wire netting is the negative pole and the system is thus made safer than ever. Spectators can stand round the pool, placing their hands in the water, and feel nothing. Fresh water is used with four tons of salt dissolved in it.
The electric apparatus is larger than might be suspected. A three-phase rectifier and transformer convert 400 volts alternating current to 100 volts direct current, there being two valves to each phase. On some outdoor pools, however, petrol motors are used.
LAYING THE PULL-UP CHAIN on a new gravity ride, or coaster, at Felixstowe, Suffolk. Cars at the beginning of the ride are drawn to the top of an inclined hoist by a chain with which cogs under the cars engage. Safety ratchets are provided so that the cars cannot run back.
The “River Caves” ride is really a concrete track along which water flows from one level to a lower level at the other end, the boats merely following the current of the water as it flows down the track. The water is kept circulating by a gas engine and a paddle wheel, which lifts the water from the lower level to the higher level. The ride itself consists of a number of scenic effects through which the boat passes as it flows down the track. The “Water Chute” is an incline down which the boat slides by its own weight. It is similar to the slopes down which many lifeboats are launched. In one park, boats of the “Water Chute” are raised to the top by an electric lift. The current at the start of hoisting increases from the normal value of 4’8 amperes up to 60 amperes. This gives some idea of the difficulties which have to be faced.
Power for these amusement devices is all-important, and the lighting for the shows is not only of utilitarian value, but also exerts a powerful psychological influence. The intermittent service requires frequent starting against load, so that the starting currents sometimes amount to ten times the rated amperage.
The old familiar steam engines generating power at travelling side-shows are being replaced by diesel engines. One American showman has built seven special wagons, each containing a 60-kilowatts diesel set and acting as a base for a collapsible steel and aluminium tower on which floodlights are mounted. These lights and tower go within the wagon for travel. The six-cylinder diesels, driving alternators, use about 4½ gallons of fuel an hour, and lubricating oil is changed after seventy operating hours.
One of the largest rides ever built, and one which marked a new development in the welding industry, was the “Sky Ride” at the Century of Progress World’s Fair at Chicago in 1933. The “Sky Ride” was, essentially, a transporter-bridge, consisting of two towers, 628 feet high and 1,850 feet apart, supporting a track cable system at an elevation of about 234 feet, on which twelve cars were suspended. The track lay over part of Lake Michigan, and travellers had a wonderful view of the Exhibition. Each tower, which was higher than any of Chicago’s sky scrapers, had a base of 110 feet square.
POWER FOR TRAVELLING SIDESHOWS at a fun fair may be provided by special 60-kilowatts diesel sets housed in wagons. The wagons act as a base for a collapsible steel and aluminium tower on which floodlights are mounted. The six-cylinder diesels drive alternators, and consume about 44 gallons of fuel an hour. The starting currents are sometimes ten times the rated amperage.
In contrast to the normal form of transporter bridge, the entire truss system consisted of wire ropes integral with the main cables, and not the conventional form of structural steel stiffening trusses. This wire-rope truss system supported four horizontal track ropes each with a diameter of 1½ in. To reduce the deflection and allow easy riding, these track ropes were counterweighted at either end, so as to be under a high initial tension.
Each of the twelve cars held thirty-two persons. There was a double deck and passengers sat back to back. Each car was suspended from an eight-wheeled trolley by a set of eight track ropes in two sets of four. The four outer wheels were merely supports, but the inner wheels were specially grooved to clutch the rope. Guides were fitted to limit the sway. The speed of the cars was about six miles an hour. In five months 3,000,000 passengers made the trip without mishap. Access to the car loading platforms was obtained by four lifts to each tower, thus providing for more than 3,000 patrons an hour. Two of the lifts in each tower went to the platform and the other two completed the journey to the top, where an observatory was built. The cars were hauled by traction cable until they reached the loading platforms, where they were taken round a curved track. At this stage they were propelled by electric motors.
In all about 2,000 tons of material and 1,000 tons of cable were used. The total cost was about 1,000,000 dollars (£200,000), and it is claimed that such transporters, stripped of such luxuries as the observatories, are decidedly economical where traffic does not warrant the conventional bridge. All these rides are as safe as engineering skill can make them. Accidents due to mechanical faults are rare and in Great Britain the Home Office, which exercises continual vigilance over machinery of all kinds, has never been compelled to intervene. The greatest danger comes from excitable people who, in a spirit of bravado, show off to their companions and do things in an amusement park which they would never think of doing elsewhere. Nearly all accidents can be traced to this source and rarely has the engineer or showman been to blame.
This is not surprising, for the engineer takes no chances. Everything is made about six times stronger than is necessary. Before being put into use, a specimen ride is made and tested to destruction with loads far in excess of any which it will be called upon to bear in everyday use. Often hundreds of pounds are spent in research and experiment. The designer can tell to a nicety how fast a car will travel down a certain slope and how much momentum it will have to send it up the next. From lessons learnt in one ride new thrills are based. On the site, too, a special staff is kept solely to test and examine the machines. Most people prefer speed to nauseating dips, and so riding devices are made to go faster and faster. From America comes the “Loop-o-Plane”, which consists, essentially, of a cage at the end of an arm revolving in a loop of 32 feet diameter. The cage is slowly raised backwards until it reaches its zenith, when it is allowed to fall forwards. The sensation is similar to a steep glide or the looping of an aeroplane, but it is quite safe and smooth and does not shake up the passengers.
Last Word with the Public
There are two models, one with a single cage which takes four adults, and another which takes twelve adults or sixteen children. The single units are powered by three or five horse-power single-phase electric motors; dual units by 7½ horse-power single-phase motors. The ride lasts about fifty seconds.
An essential feature of rides of this type is that they have to be easily dismantled, transported and set up again, as well as requiring the minimum amount of staff to operate them. As for the “Loop-o-Plane”, one man, perhaps with a helper during rush hours, can sell the tickets and operate the machine. Designers have to bear these things in mind. Another thing the engineer has to consider is the psychological side. Why do people ride these devices? When the British Association met in Blackpool recently, they debated this point. The managing director of the Blackpool Amusement Park told these scientists something about the modern amusement devices. Modern life, for most of us, is lacking in thrills and excitement. The showman provides them. Rides such as the “Ghost Train” pander to our curiosity and fear of the unknown. Other rides exploit the fear-escape propensity. The “Auto-Skooters” help us to be aggressive harmlessly. In sensational rides the ladies instinctively turn to their male escorts for protection. Though the showman provides the thrills, the public are the final judges.
At Blackpool, the amusement park has entered the realms of serious architecture. It is now planned by an architect as a coherent whole, instead of being a miscellaneous collection. Thus the architect worthily houses the engineer’s contribution to the amusement of holiday makers, and the engineer’s devices truly reflect the modern mechanical trend.
REBUILDING THE BLACKPOOL SCENIC RAILWAY. Two trains, each of three cars, run on separate tracks simultaneously. A maximum speed of 72 miles an hour is reached, and at its highest point the track is 72 feet above the ground. Materials used for building the railway included 500,000 feet of pitch pine and 139 tons of steel.