Motor Fire Appliances Used in London*
Before entering on the subject of motor fire appliances, a brief explanation of the system adopted in London of dispatching appliances in response to calls is subjoined, in order that the conference may understand the duties required from the various types adopted. The area to be protected is 117 square miles, which, with the exception of the public parks and some small areas at the extremities of the metropolis, is entirely covered with buildings. There are at present for this area 85 land fire stations and three floating stations; of the former 18 are entirely equipped with motors and 12 partially so. Each station is equipped with a fire-escape van carrying a ladder capable of being extended to at least 50 feet, and also furnished with supplementary ladders, hose and tools for getting to work from hydrants, and a cylinder holding about 80 gallons of water, fitted with 180 feet of rubber garden hose, 3/4-inch inside diameter, for extinguishing small fires. This appliance, the crew of which is on duty night and day, is ready for an instantaneous turn-out and only attends fires on the ground immediately protected by the station, the distance it may travel to fires rarely exceeds one mile. The yearly mileage of escape vans is about 600 per machine. Most stations are also equipped with an engine or motor pump, and in a few localities with two engines, all of which carry hose, etc. These engines, besides attending fires in the vicinity of the stations at which they arc kept, are considered available for service at any fire in the area protected. The yearly mileage may be taken at 1,200 per machine, but in addition they perform heavy duty, pumping at fires sometimes for 24 hours without intermission. Stations in localities where there are many high warehouse buildings are equipped with long ladders extending from 75 to 90 feet. These appliances, while intended, generally speaking, for attending local calls, are considered available in case of serious fires in high buildings within a radius of about five miles. The yearly mileage run docs not exceed 1,000 per machine.
Other motor appliances in use are lorries for carrying on from the central stations coal and oil fuel for the steam fire engines, petrol for motor pumps and also additional hose and acetylene water lights, etc., to large fires, and delivering stores regularly to stations. Tenders for taking on the principal officers and their orderlies to fires, and also self-contained oxygen smoke helmets, cellar pipes, marine torches (acetylene), etc. Instruction tenders for training the men undergoing instruction in motor driving. These are not the oldest motor appliances available, but modern ones with chasses similar to those in use for pumps, escape vans, etc. Motor cars for officers have been in use since 1901, and shortly after that an attempt was made to draw an existing land steam fire engine by a motor tractor, the front axle being removed, making altogether a sixwheeled appliance. It was found impossible, however, to travel at sufficiently high speeds with this without undue skidding, and the principle was abandoned. In 1902 an existing steam fire engine was converted to a motor engine by providing a separate engine for propulsion, the steam being supplied by the fire engine boiler. After a time, however, this was abandoned and the appliance was reconstructed for horse traction. The first success in replacing horsed fire engines and horsed escape vans by mechanically driven vehicles occurred in 1905-1906, when steam motor fire engines and petrol motor escape vans were obtained. With the former it was found that as the appliance had to be ready for an immediate turn-out, a pressure from 80 to 100 pounds per square inch bad to be maintained in the boiler, and owing to the excessive vibration on this type of boiler on the road necessitating considerable repairs, and also to the large expense incurred in maintaining this pressure by gas, the steam system was abandoned.
With regard to the petrol motor escape vans, the first supplied only gave moderate satisfaction, as manufacturers generally had no experience in the running of motors (weighing about 11,200 pounds with load) at speeds exceeding 20 miles an hour to guide them, the principal defects being under-tiring, want of sufficient strength in the fittings to withstand the excessive vibration, and inadequate springing. Indeed, prior to 1910 it was considered necessary to have one spare escape van for every one on duty, in order to maintain an efficient service, whereas at present only one spare in five motor escape vans or motor pumps is necessary. The experience with early petrol fire engines fitted with pumps was somewhat similar. From the first introduction of heavy engines capable of high speed the problem of providing a satisfactory non-skid engaged attention. Some mitigation of the inconvenience was found by utilizing chains festooned diagonally across the tires, but considerable damage was caused to the rubber, which, when worn, allowed the chains to come in contact with the iron rims, causing the non-skid chains to break and not unfrequently jam in the driving chains, or to allow the loose ends to tear the mud-guards, etc. Other devices were tried to check the tendency to skid, such as studded leather covers and transverse bands of steel-studded balata belting fitted into slots cut into the rubber of the tire. The latter were found to be most effective when tires and bands were new, but gave endless trouble when partly worn. One motor pump was fitted experimentally with a groscope behind the radiator, but it was removed, as a swaying motion was set up when traveling at high speeds. In addition to this, the steering was rendered uncertain. One appliance has run for a year without non-skids but with softrubber tires of flat tread and extra wide section, single on front wheel, twin on hind wheels; although no skidding has taken place there is still some doubt if fire engines can be safely run under all conditions in London without some non-skid attachment. Front-wheel brakes were tried on the appliances supplied by different manufacturers in 1910 in order (it was hoped) to obviate the effects of skidding, but while satisfactory results were obtained on tests they were found unsuitable in practice, and have now been removed from the appliances and rearwheel or differential brakes fitted in lieu. The difficulties formerly experienced have now been fairly overcome as follows:
*Read at Convention of International Association of Fire Engineers in New York, Sept. 21, 1913.
(a) By careful training and the continued experience of drivers.
(b) By allowing greater cross-section in tires.
(c) By extra heavy leather steel-studded covers fitted on two wheels only, one front wheel, one hind wheel.
The author has up to now referred only to the early attempts to introduce motor traction in the place of horses, and the experience gained was extremely valuable both to the fire brigade offiicials and the manufacturers. It is now proposed to deal only with what may be termed motor appliances at present in use:
- Escape vans.
- Turntable ladders.
ESCAPE Vans.—Perhaps the most successful type of appliance to be introduced has been the electric-motor escape van, tor service in localities where only moderate gradients arc encountered, the first of this kind being obtained in 1911.
The power is provided by a battery of 84 cells of 195 ampere hours capacity, giving a normal running output of about 30 horsepower. The appliance runs about 30 miles on one charge if necessary, but owing to the nature of its service it stands fully charged, ready to give out the maximum output on receipt of a call. The motors are in the front wheels, the fields being fixed to the stub axle, around which the armature revolves with the wheel. The tires are single 5-inch on all wheels. There are electric brakes on the front-weel motors which are valuable in emergencies, while two mechanical brakes on the rear wheels are sufficient under ordinary conditions. The control is of the seriesparallel type, with five notches forward and reverse, and two brake positions. The weight of the appliance ready for running, but without ladders, hose and small gear and men, does not exceed 8,300 pounds, the total weight of the machine complete being about 11,800 pounds. A speed of 25 miles per hour is maintained with full load on a level and good road, and the machine is capable of ascending a gradient of 1 in 8, full laden, at a speed of about six miles per hour, or a moderate gradient at 15 miles per hour. The weight of the appliance fully lauen is about 600 pounds more than a corresponding petrol van. Undoubtedly, petrol motor escape vans are required for localities where stiff gradients have to be encountered.
The type found satisfactory has the following general features: Four-cylinder engine, 5-inch bore by 5 1/8-inch stroke, giving about 50 British horsepower; double ignition, i. e., Bosch magneto and accumulator and coil; speed about 30 miles per hour. The engine is started up in the station every four hours, day and night. Where the engine room at the station is not warmed with hot water or gas radiators, electric heaters are hung over the front of the radiator to warm the engine and keep it ready for an Immediate start in cold weather. The appliance weighs about 11,200 pounds fully laden, and has 4 1/2-inch tires on front wheels and 5 1/2-inch on rear.
Pumps.—A modern petrol pump used in the London fire brigade has a four-cylinder engine, 5-inch bore and 7 1/8-inch stroke, giving 58 British horsepower at 1,000 revolutions per minute, and 65 British horsepower at 1,100 revolutions per minute. Speed, 30-40 miles per hour. Weight, about 11,200 pounds fully laden with men, gear and hose. Tires are single 4 1/2-inch front and single 5 1/2-inch rear. The pump is centrifugal (usually termed turbine) and geared up from the engine. It is placed at the rear of the appliance and can be controlled from there or from the driver’s seat. It is now found that for London the two, three or four-stage centrifugal pump is capable of fulfilling all the required conditions, and only this type has latterly been specified. The pump gives an output of 500 English gallons (American, 600 gallons) per minute at a working pressure of over 120 pounds per square inch. There is a considerable controversy among fire engineers in Great Britain as to whether the reciprocating or centrifugal pump is the most suitable for the duty required of fire engines. The mechanical efficiency of the reciprocating pump is 10 to 15 per cent, higher than the centrifugal, the pump can run slower when discharging a small quantity of water at high pressure and can pick up its own water when drawing from a canal or dock without the aid of a vacuum pump, which is necessary for the latter. The centrifugal pump has to run fast in order to obtain even a small quantity at high pressure. On the other hand, when delivering at lower pressures a larger volume can be delivered than from the reciprocating.
One great advantage of the centrifugal pump is the possibility of working two pumps in series when a high pressure is icquired, or in parallel when a large volume is required from one jet. Under the former conditions an efficient jet was thrown over the top of St. Paul’s cathedral, 340 feet above pavement level. The jets commonly obtained from standard large-sized American steam fire engines can also be obtained by working two of the smaller capacity motor pumps as described above. In London it is necessary that in addition to the pump, at least 600 feet of rubber-lined canvas hose 2 3/4 inches inside diameter, besides the necessary small gear (see appendix) and five men must be carried. The speed of the appliance is greater than that of motor escape vans. Although at present in the outlying suburban stations smaller horsed steam fire engines are stationed than those in the central area where the fire risk is greater, it has been found better to equip the former stations with the same sized motor pump as in use elsewhere, as the additional distance to be covered need not be considered as in the case of horsed engines.
TURNTABLE LONG Ladders.—At present the brigade is only equinped with two motor turntable long ladders. These can be extended to a height of 90 feet and can be safely used as a water tower at a height of 60 feet. In both cases the system of propulsion is by electric storage batteries and hub motors in the wheels. In one design the wheel motors are interchangeable with those on the motor vans for carrying escapes. and drive on the front wheels. In anothetype the battery is of the same capacity and manufacture. but the motors are fitted to the rear wheels. It is not considered necessary to snecify for these appliances to travel at a speed of more than 20 miles per hour. The total weight of the appliance with ladders is about 13,800 pounds.
It is probable that by adopting motor long ladders a number of the existing horsed long ladders will be dispensed with, two of which are being adapted for electric traction.
Lorries.—The first lorry to be procured was a standard five-ton (11,200 pounds) machine from one of the largest lorry builders. It is fitted with a four-cylinder engine, 5 1/2-inch bore and 6 1/2-inch stroke, having an output of 55 British horsepower at 1,000 revolutions per minute, and is capable of a speed of 30 miles per hour. It is fitted with 5-inch tires on front wheels and twin 5-inch on rear; no non-skids are provided. A covered hood is fixed. A second lorry has been ordered. This will be of the standard three-ton (6,720 pounds) type, similar in most respects to the larger machine; it will have a four-cylinder engine, 4 3/4-inch bore and 5-inch stroke, giving an output of 45 British horsepower at 1,000 revolutions per minute. The machine will be kept at the chief station in one of the districts and will be used in a similar manner to the other appliance.
MOTOR Tenders.—Those at present in use for carrying principal officers to fires, and other work, are standard chasses by well-known makers; in one case large pneumatic tires 35 1/2 by 5 1/2-inch (895 by 135 millimeters) are fitted, with detachable rims. On this machine four men are carried besides the gear mentioned previously, the total weight being 4,410 pounds, and no trouble has been experienced with the pneumatic tires; indeed the instruction tender, which is of similar pattern and drive, has also been recently adapted for pneumatic tires instead of solid ones. At some suburban stations motor tenders are allocated in addition to the motor escape van, that in the event of the latter being required elsewhere the tender may be at once dispatched with sufficient men, hose, hook ladders, etc.
MOTOR Cars.—The cars in use, of which there are 13, are of standard pattern by well-known makers, and are mostly fitted as touring cars. They are used both for inspection work and also for proceeding to fires. The superintendents in each of the six districts are now provided with two-seated touring cars for daily inspection of the stations in their districts; also for taking them on to fires. Smoke helmets are carried in these cars.
The author has not endeavored to enter into details of the appliances, but subjoined are complete specifications of the principal machines to which the makers have to tender, and in connection with this it has been found advisable to restrict the number of types in the service, in order that the drivers, when transferred from one appliance to another in the station or district, can drive the appliance efficiently. In future endeavors will be made for only machines of one make to be allocated to a station. In the early days of motors, specifications were drawn up by technical officers of the brigade, but with the exception of details it is now found advisable for the manufacturers to supply their standard type of chassis adapted to the conditions of the London fire brigade, as they are in a position to replace any parts instantly from stock. Perhaps one of the most important points with regard to the application of motors for fire brigade work is the question of the cost compared to horsed appliances. In the early stages it would not have been correct to say that any saving was shown in favor of motors; indeed the reverse was the case, but with the improved standard commercial type chassis which has been adopted, and the continued experience of the drivers, there is undoubtedly a saving effected by motor appliances. The London fire brigade owns no horses; they are hired from the contractors at an average rate of £70 per annum per horse. This sum includes bedding, fodder and harness. The contractor also takes all risks. The following figures give comparison between the cost in maintenance of horsed and modern motor appliances, the repayment of cost of horsed appliances being spread over 25 years, and for motors 10 years:
From the above it will be seen approximately that the saving with motor pumps is about £40 per machine per annum; petrol escape vans about £l7, and for electric escape vans about £5 as compared with similar horsed appliances.
The total number of motor appliances required to complete the conversion of tne brigade irom horsed to motor traction, in addition to those at present in the brigade and on order for this year, will be as follows:
Escape vans (petrol or petrol-electric). 31
Escape vans (electric)… 32
Motor pumps (petrol or petrol-electric). 64
Motor turntable ladders. 33
Motor lorries. 9
Motor canteen van. 1
Motor cars . 3
Total . 162
It is estimated that the cost for the above future appliances will cost about £150,000.
The present equipment of the brigade, including the appliances on order, is as follows:
Escape vans (petrol). 22
Escape vans (electric). 11
Motor pumps (petrol). 30
Motor turntable ladders. 4
Motor lorries . 2
Motor tenders . 5
Motor cars . 13
Total number of appliances. 87
The ultimate total number will be.249
There are also in use two motor fireboats as well as two steam-driven vessels.
(a) London fire brigade specifications as drawn up for tender, with notes from makers’ specifications, or the latter in detail.
(b) List of gear carried on the various appliances.
(c) Map of London, showing fire alarms and locality of stations equipped or partially equipped with motor appliances.
(d) Photographs of different motor appliances in use.