INENTAL SYSTEM FOR BIRMINGHAM
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Dustless Collection, Tried, Proved and Accepted, Now to Cover the Whole City By P. A. C. Brockington,
MUNICI P.A L undertakings throughout the country have been keenly interested in the dustless collection pilot scheme started by Birmingham Salvage Department 'last January with four vehicles. The approval of the city council, on April 21, to extend the scheme to cover the entire city area followed highly favourable reports on its operational advantages.
It represented a precedent of first importance because it was the first example nationally of a comprehensive dustless system being sanctioned for a major centre of population. A development period of 1-0 years is regarded as the maximum for applying the scheme to all the city districts. It may be fully operative in about eight years.
Additional Cost According to an estimate from the salvage department (The Commercial Motor, April 24), the additional cost of dustless collection in the first year Will be f45,450 to f49,050,-and &erall application of the scheme will increase the cost by £1.35,990 to £171,090. Corresponding increases in the td. rate will be.0.66d. to 0.71d. in the first year, and 1.98d. to 2.49d. in the final year.
In the system that is being superseded by dustless collection, the loader empties the bin into a plastics skep on the householders' premises. His walking distance is thus reduced by 50 per cent., compared with the movements of a loader when the conventional method of carrying the bin to the vehicle is used.
To assess the economic factors of dustless collection, it is necessary to allow for the extra distance covered by the collecting personnel in handling the special bins which
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Would not be necessary if it were compared with a typical system.
The dustless scheme almost eliminates bin lifting, is far cleaner for the operating personnel and keeps premises 'and streets free from spilled refuse.
Machines employed for the pilot scheme comprise four Eagle Speedyload 16-cu.-yd. outfits based on Austin long-wheelbase oilengined 7-ton chassis with forward ' control and one German Haller collector of the same capacity, supplied by Glover, Webb and Liversidge, mounted on a Commer chassis, which is also an oil-powered 7-tonner.
The capital outlay in both cases represents an increase of some 50 per cent, compared with the cost of conventional vehicles of ' comparable capacity. The extra expenditure on special bins is proportionately of the same order.
Operation of the vehicles is arranged to conform to the department's "traditional" system, whereby the vehicles complete threerounds in
the day and ,return to a depot after each trip to deliver refuse to separator and incinerator plants. An essential part of the system provides operators with the opportunity to use the canteen facilities provided for snack meals at breakfast and tea-time and for a cooked mid-day meal.
Vehicles in the pilot scheme collect refuse in the north sector of the east area and deliver it to the Montague Street depot, an average journey of nine miles. Although the existing capacity of the plant at the department's five depots is not sufficient for the tonnage of refuse collected, a new depot in the south area, and later a second depot of increased capacity in the east area, will obviate the need for using tips for the disposal of a proportion of t h e refuse.. The availability of tipping sites is somewhat limited, and no sites would be available in the city area in a few years' time if direct tipping were continued indefinitely.
Collections are made weekly and, on average, the work in a five-day week by each of the new machines entails visits to some 3,000 premises, an average of about 200 premises per round. Four vehicles are regularly employed and one vehicle acts as a stand-by. Approximately 11,000 premises 'are now covered by the scheme, from a combined total of approximately 320,000.
Each machine is operated by a team of seven men, comprising .driver, four collectors and two loaders. Two of the collectors go ahead of the machine with lightweight trolleys and transfer the loaded bins to the kerbside. A row of bins is, therefore, in position for loading when the vehicle arrives at the premises. The loading operation is normally completed by the two men in about 15 seconds. The remaining collectors are, in effect, bin distributors, for they return the empties to the premises, using the same type of trolley.
Both types of vehicle are equipped with a Zoller air-operated shutter at the rear of the body, and the bins are lifted about 3 ft. to enable a crosspin to be located in a hook. By the movement of a lever the bin is then emptied into the body by the action of the pneumatic mechanism. This raises a pivoted arm which lifts the bin and tilts it forward so that a tongue on the lid engages with a bracket in the shutter.
In the next operation the bin is raised to the full-tilt discharge position, and at the same time the lid is opened upwards on its hinges inside the vehicle and the reinforced rim mates with a seal on the shutter. After being shaken mechanically (the Birmingham loaders prefer to perform this job manually), the bin is returned to its original position by the operation of another control lever.
One Manual Lift
Raising the bin to shutter level is the only manual lifting performed by the members of the team and, according to the Eagle company, even that may soon be eliminated. A hydraulic lifting device is being introduced, which will enable one man to load a full bin. In this case, a hydraulic ram mechanism would replace the pneumatic cylinder of the shutter.
The special bins are of 21-cu.-ft. capacity and the container section is of the standard type. Following standard German practice, the lids incorporate a number of individual features in addition to those mentioned in earlier paragraphs. These include, in the centre, a palm hold in the form of a dome, which facilitates manual handling.
Weighing 3 lb. empty, a bin is normally loaded by the operator on a trolley with one hand, and the trolley can be wheeled to the vehicle with the minimum effort. Experiments have been made with bins of 3-cu.-ft. capacity having a similar lid.
Bins are loaned on a rates charge in all areas, and the higher cost of the special bins may be partly or wholly offset by an increase in useful life, compared with the average of eight years. The elimination of lifting and ease of movement should reduce damage to a minimum (none has been damaged since the scheme was started) and, even more important, these facilities should remove the most common cause of physical injury.
The possibility is being considered of providing staff with clothing now more appropriate to the cleanliness of the job. It should also be possible to retain the services of older men.
Before the pilot scheme was introduced an estimate of labour requirements was prepared by the department. It forecast that dustless collection would necessitate an increase in staff of about a third. Operation of the scheme has shown that this estimate was valid.
Whilst the department are confident that both types of machine will have a useful life of more than 10 years, an accurate estimate of maintenance costs cannot be made. Ample facilities exist, however, for the repair of wearing parts.
Apart from the common use of a Zoller shutter, the Eagle and Haller systems are basically dissimilar. In both cases, however, the refuse discharged from the bin is tipped into a rotating elevator.
The elevator of the Eagle system, which is based on the German Kilka design, takes the form of a bucket wheel, which rotates at about 4 r.p.m. and carries the refuse upwards to a chute by means of spring-loaded blades. From the chute, the refuse is discharged into a rotating drum in unit with the bucket wheel. An outstanding feature of the drum is a continuous spiral or hollow worm, attached to the, inside surface. -Movement of -the drum propels the refuse forward and compresses it. The refuse is discharged by continuing rotation in the same direction, which carries the material towards the hinged rear door. Discharge is completed without tipping in six to seven minutes.
In contrast to the Eagle system, the Haller internal mechanism incorporates a full-length distributor worm located near the top of the body. This is of relatively small diameter and carries the upper layers of refuse towards the front of the container and distributes the material evenly in the free space available.
Discharge is by tipping by an underbody single hydraulic ram. Free movement of the material is facilitated by the upward • displacement of the rear section, together with the roof and distributor worm as a unit. This is performed automatically by cables as the body is tipped.
A notable feature of the Haller body is the provision of side doors at the front. These can be used by the operatives to load bulky or "odd lots" of refuse which cannot be deposited in the bin.