ROLLERS AND MOWERS FOR PUBLIC SERVICE.
Page 25
Page 26
If you've noticed an error in this article please click here to report it so we can fix it.
Why New Types of Roller have been Found Necessary ; a Survey of the Appliances in Use. Motor Mowers for Parks and Playing Fields,
M0DERN methods of road construction, and particularly of road surfacing, have necessitated the development of rollers differing considerably from old-time conceptions. Naturally, with thousands of miles of macadam still in existence, the ordinary type of roller is still employed to a considerable extent, but bituminous caipetings require different treatment, and the type of appliance which has proved most popular is the tandem roller with the-weight evenly balanced between the two rolls, a low centre of gravity, as compared with the width of the rolls, so that sideway rocking does not occur, and quiek-reversing gear which prevents dwell at the reversing points, this dwell, in the case of comparatively plastic surfacing material, might cause sinking of the rolls and result in uneven surfacing. In most cases also, it is desirable that the rolls at each end be divided and, in the case of driving rolls, be fitted with differential gearing so that easy turning is permitted without rucking and ridging the 'surface.
It must not be thought, however, that improvements have not been made in the three-roll machine. This is far from being the ease: A number of motor-driven types have been placed on the market, and in addition to these considerable modifications have been made in many of the steam-propelled types, and some of these rollers can also be used with success on asphalt and other materials of this nature.
One of the most interesting of the steam type is the Advance built by Wallis and Steevens, Ltd. It is claimed for this machine that it will meet the needs of special carpeting and ordinary rolling, and it affords equal distribution of weight over the whole rolling surface, the compression weight given by the front and rear rolls being practically equal. One striking feature of the machine is that the rolls, being specially sprung, automatically edjust themselves to the road camber, and the lowering of the centre of gravity obviates side sway. In addition, the forecarriage can be locked and the engine is designed to give rapid reverse.
Two interesting types of machineare built by Sir W. G. Armstrong Whitworth and Co., Ltd. One is a modified threeroll machine, in which the chief features are the use of eaststeel for the fork and forged steel centres fur the wheels, whilst the other is a tandem type with quick reverse, and can be used for longitudinal, zig-zag, diagonal or transverse rolling. The latter model is propelled by steam and is steered by engine power.
John Fowler, and Co. (Leeds), Ltd., have long been noted for the quality of their products, and this extends to their steam-rollers, which are made in various weights. The chief features of these machines lie in the boiler and cylinder, the boiler being a modified Relpaire type, which can standup to many years of hard work, whilst the cylinder is steam jacketed, thus avoiding losses through condensation, Three sizes of motor roller are also made.
The range of rollers built by Marshall, Sons and Co., Ltd., include those of the ordinary type with piston-valve engines and the Millers-Marshall tandem type with rapid reverse gear, which is built in five sizes from 6 tons to 10 tons.
The boiler is a vertical multi-tubular type and the twin. cylinder engine is carried horizontally on the main frame, thus giving a low centre of gravity. Few makers have had so much experience in roller construction as Ruston and Hornsby, Ltd., who make standard
type appliances and quick-reversing motor rollers of the threeroll and tandem types. A point in the design of bath the latter types is that the gears are not disengaged when reversing, a separate clutch being used for each direction. thus promoting safety on hills and saving wear and tear on the gear teeth. An extra low bottom gear allows travelling quite as slowly as is possible with a steam-roller. In the case of the tandem type, provision is made for water-ballasting the rear roll.
The power units consist of two-cylindered• paraffin engines in which petrol is used for starting. The Clayton road rollers are of the tandem type, and are made in sizes of 5, 6, 7 and 8 tons. The engine in each case is of the compound type, mounted above a loco-type boiler.
Two speeds are provided, and the final drive is by means of a heavy roller chain.
A well-known and successful roller of foreign make is the fly, constructed to run on petrol or oil. This is a threeroll machine in which steel castings are used instead of castiron. In its general design it resembles a steam-roller, the radiator taking the place of the boiler, whilst the engine is situated in the cab. It is made in sizes varying from 6 tons to 12 tons. The power units of the two light types have two cylinders, and those of the two heavier types four cylinders.
Three-wheel and tandem-type water-ballast motor rollers are built by Barford and Perkins, Ltd., who have had 18 years' experience in the construction of motor appliances of this kind. The characteristics of the special rollers for road use are short wheelbase and low centre of gravity, and the whole of the transmission, with the exception of the final chain drive, is enclosed in oil-tight casings. In the ease of the three-roll type, the overlap is unusual, it being some 4 his, at each side. Petrol or paraffin may be employed as fuel. Apart from these machines the company manufacture a large number of models suitable for rolling paths, etc.
Rollers of the light type, weighing 2 to 2i tons, and with a rolling width of 5 ft., are built by Thomas Green and Son, Ltd., for work on pleasure grounds and similar places. These are water-ballasted, and have four-cylindered engines, three speeds and reverse gearing.
One of the tasks which face municipal authorities is that of keeping in suitable order the grass of parks, public spaces and recreation grounds. This often entails a large amount of labour, and involves considerable time unless motor-propelled mowing machines are employed. It may, therefore, be of interest to give a brief résumé of some of the best-known types on the market.
For instance, Dennis Bros., Ltd., make a most reliable machine, which has been newly designed from start to finish, and is not merely an adaptation of an existing type. It is made in two sizes, the widths of the cutting cylinders being 24 ins. and 30 ins, respectively, the larger machine being that most suitable for public service. A trailer seat can be fitted to either, and the 4 h.p. engine is powerful enough to draw trailer and driver up steep gradients, and to enable a speed of 5 m.p.h. to be maintained on the level.
If required, the machine can be used as a roller only, as the grass-cutting mechanism can be thrown out of gear.
The engine is air-cooled, a current of air being directed on to it be a fan running on ball bearings. The main rollers are made in three sections, and the roller shaft is mounted on ball bearings end provided with a different gearing permitting easy turning. Two Perodo-faced cone clutches transmit the power to the roller and the cutting cylinder.
The machine recommended by by Thomas Green and Son; Ltd., for municipal work is their 42-in. model. This has a four-cylinder engine with a radiator mounted at the right of the driver's seat, tiller steering and a reversing gear. The front portion of the machine is hinged, thus enabling the cutter to adjust itself to irregularitie'a on the ground, and the cutter can be trown out of gear for simple rolling.
A small type of machine whitth has proved Very popular with municipalities is the Atco, made by Chas. H. Pugh, Ltd. This machine will cut 1;000 square yards of grass in 20 minutes at a fuel cost of about lid. It is made in three sizes, 16-in.; 22-in., and 30-in. (Ourfigures are given for the 22-in. model.) The cutters have 12 blades, and a cutter release is provided, so that the machine can be wheeled backwards and forward as required. . A machine with a large work capacity has recently been produced bY Ransornes, Sims and Sefferies, Ltd. This has a 42-in. cut, and is provided with a four-cylinder petrol motor of 11 h.p. The :power is .conveyed.hy chain to the driving rollers and cutting cylinder, and the complete swing frame can be lifted up to throw the weight on the land rolls, when
required: Other mowers ranging in size from 16 ins. to
36 ins. are also manufactured. , A neat little maehiiM With a 27-in, cut and a small aircooled engine is marketed by Lloyds and Co. (Letchworth), Ltd. Each of the driving wheels has an individual clutch of the dry-plate type.
An efficient 16-in, machine called the Automo has been evolved by F. Mitchell (Nottingham), Ltd., who employ the J.P. Super mower and an engine of 1i h.p.