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HOW SHAL TIP?
Page 76
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Page 78
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4 Review of Tipping-gear Types ind Makes, and of the Problems Encountered by Both Manufacturers md Operators in Fitting Specific Units for Particular Kinds of Work
by a Special Correspondent
IN a review of tipping-gear types and makes it is appropriate to present a deliberately confused picture of tipping vehicle problems The majority of vehicles engaged in site work carry a greater load than the vehicle makers' rating for the model, and there are large variations in load distribution because of the different types of body fitted.
Composition of the material carried may vary widely from day to day. Speed of tip may, or may riot, be of first importance, depending upon the average number of tips a day, and the importance of rigidity of the complete structure, including the chassis frame and bodywork, is a function of ground surface conditions. The vehicle which operates satisfactory when tipping is restricted to sites with a hard level surface, might be quite unsuitable for more typical site conditions. .
Many users "ask for the impossible" when they overload a standard tipper or, without expert knowledge, authorize a combination of chassis, tipping gear and body, with strict limitation on overall weight and cost. It is, therefore, normally impossible to assess the optimum characteristics of a tipping vehicle unless full details are known of operational requirements. Two users may have opposite views on the most suitable type of tipping gear for a seemingly similar job. They may both be right.
The tipping gear maker should, therefore, be a psychologist as well as a technician. Ideally, he should be adamant in refusing to supply a gear for equipping an unsuitable vehicle carrying an
unsuitable body, but this is often impossible. The succes! of a particular tipping gear in a given application is ofter the result of close liaison with the chassis maker, the body builder and the operator.
According to technicians of Telehoist, Ltd., Manor Road Cheltenham, the vehicle chassis should provide a stable platform for the equipment, particularly in the case ol multi-wheelers used for rough site operations. Lightweight long-wheelbase chassis and vehicles converted into multi. wheelers by the addition of a trailing axle are, in typical cases, considered unsuitable on uneven or soft ground.
It is emphasized that body structures should afford adequate torsional rigidity tc avoid distortion, and it i! pertinent that users who dc not purchase the gear complete with auxiliary equipment art supplied with a diagram show. ing the recommended layout ol the sub-frame and cross bracing members.
Correspondent
When a vehicle maker arranges to specify Telehoist gear and body as standard equipment, the vehicle is subjected to a tilt test before the assembly is approved for the application. This consists of tipping with a diagonally disposed load with one rear wheel jacked up to a height of 12-14 in.
With regard to the proposed plating regulations, their introduction would, it is considered, necessitate " re-thinking " on the part of tipping-gear manu
facturers. In existing conditions the makers must cater for overloads up to 66 per cent.
Limitation of payload by law to comply with the chassis manufacturers' ratings can be expected largely to obviate overloading as a necessary feature of normal operations in a competitive market, and it would then be possible to use lighter tipping gears with adequate capacities.
Commenting on the need for a stiff structure, an executive of Pilot Works, Ltd., Manchester Road, Bolton, Lanes, stated that until chassis manufacturers can see their way to producing deeper frames specially for extra longwheelbase tippers, together with suitable reinforcing angles at the appropriate points, the company will continue seriously to recommend all users of long-wheelbase tippers to consider the benefits of having a sub-frame fitted to their chassis.
Dangerous Practice
Fitting tipping gear for arduous site work on to a chassis other than a• model designed by the manufacturers for tipping work is regarded as a highly dangerous practice by Welford Engineering (Oldbury), Ltd., Hainge Road, Tividate, Tipton, Staffs. It is pointed out that distributors
of well-known makes of chassis frequently condone the use of a chassis intended by the manufacturers for haulage operations on normal roads, despite the advice given by the makers, and the warning is given that applications should be restricted to special tipping chassis.
Akin to this practice is the use of a long-wheelbase vehicle as a tipper against the advice of the vehicle maker. Employing unsuitable chassis and tipping gear is normally demanded by the operator on the score of reduced weight (and higher payload), or because of the lower cost. Makers of a very wide range of tipping gears, EdbroB. and E. Tippers, Ltd., Quebec Street, Bolton, Lanes, report that the front-of-body type is becoming increasingly popular in all parts of the world this side of the Iron Curtain. Their complete range covers lifting capacities
from 5 tons to 30 tons, and it is claimed that variations of the 10 basic types of front-of-body, underbody and slant
gears amount to many thousands of types.
All the tipping gears produced by the company are powered by a sixor nine-cylindered wobble-plate pump, the moving parts of which are immersed in oil. The pump is combined with a special power take-off, produced by the company, which can be applied to virtually every make of British vehicle and many Continental and American types.
A maximum lifting capacity of 20 tons is provided by the front-of-body gears and the underbody type caters for lifts up to 18 tons. In the case of the slant-type rams, capacities vary up to 12 tons and the highest rating of the range of three-way rams is 11 tons.
In addition to manufacturing front-of-body, underbody and slant gears, Pilot Works produce a horizontal type which operates in conjunction with fulcrum arms, rollermounted on steel tracks. Fluid is supplied by a Pilot rotary-gear pump in every case.
Front-of-body types cover a lifting range of 6 tons to 18 tons, whilst the capacities of the standard underbody range cater for loads of 5 tons to 18 tons. Underbody dumper gears are designed for lifts of 10 tons to 18 tons.
In addition to slant-type and vertical underbody gears, the Telehoist range includes underbody three-way gears and the now well-known Telelever compound-linkage type.Slant-type models cater for capacities of 5 tons to 10 tons, and lifts up to 20 tons are included in the ratings of the underbody gear, all of which are twin-ram models.
Telelever gears are designed for capacities of 7 tons to 16 tons, the twin-ram unit designed for 10-14-ton sixwheeled chassis being of the double-acting type, giving an angle of tip of 70°. A similar angle of tip is provided by the single-ram double-acting gear, suitable for 6-9-ton vehicles.
Lifting loads of 5 tons to 12 tons are covered by the three-way gears, the rams of which are universally mounted. High-level mounting is available for vehicles required for tipping into the hoppers of road-laying machines.
Wide Pressure Range
Gear pumps, of the medium-pressure type and swashplate pumps in medium-pressure and high-pressure form are produced by the company. Maximum operating pressures vary from 1,000 p.s.i. to 3,500 p.s.i.
Equipment produced by the Spenborough Engineering Co., Ltd., Union Road, Heckmondwike, Yorks, incorporates either displacement-type or piston-type rams and includes front-of-body, underbody, and three-way tipping gears. A special type of combined swash-plate pump and power take-off gearbox operates at a maximum speed of 750 r.p.m. and displaces 1 cu. in. of fluid per revolution.
Capacities up to 20 tons are covered by the front-of-body gears, the twin-ram type being used in conjunction with a sliding-block stabilizer. Twin-ram underbody gears are produced for short-wheelbase vehicles in the 5-ton category, and lifting loads of 4 tons to 10 tons are covered by the three-way tipping gears. Features of a series of handoperated gears, having capacities up to 6 tons, include a trunnion-mounted telescopic ram and single-acting hand pump, Single and twin front-of-body lifting gears, slant-type underbody hoists with single or twin rams, vertical underbody gear of the twin-ram type and three-way hoists with single or twin rams are produced for rigid vehicles by Autolifts and Engineering Co., Ltd., Highfield Works, Highfield Road, Blackburn. The range also includes single and twin front rams for semi-trailers and a twin-ram underbody trailer unit.
Swash-plate Pump All the lifting gears are powered by a seven-cylinder swash-plate pump, which is combined with a power take-off and fitted direct to the gearbox. In every case the standard type is designed to give an angle of tip of 45°-50° with the rated load. Front-of-body gears provide lifting capacities up to 20 tons, whilst the maximum rating of the slant types is 12 tons.
The most powerful twin-ram underbody hoist is capable of lifting up to 18 tons and the three-way gears can lift loads up to 11 tons. Models designed for trailers have ratings up to 20 tons. A rack-and-pinion type stabilizer is a special feature of the lifting-gear equipment produced by The Milshaw Tipping Gear Co., Ltd., Birch Lane Works, Rooley Lane, Bradford, 5. The stabilizer is recommended for longwheelbase vehicles equipped with the company's front-ofbody gears, which have capacities up to 20 tons. Underbody models having a similar maximum rating can be supplied for mounting inside the chassis frame or for outrigging from the frame.
Gears of the three-way type are produced to customers' requirements and cover capacities up to 14 tons. Body sub-frames of steel or aluminium alloy are offered for all applications. High-pressure plunger-type pumps manufactured by the concern have outputs of 21 g.p.m. at 750 r.p.m. and 2,500 p.s.i. up to 8 g.p.m. at the same speed and pressure.
Piston-type Rams
Special features of the lifting gears produced by Anthony Hoists (Successors), Ltd., Braintree Road, South Ruislip, Middlesex, include piston-type rams and a shaft-driven pump of the floating-gear type in which both driving and driven gears are mounted on a splined shaft.
One model comprises a single-stage direct-acting slanttype gear, the pump of which forms an extension of the base, whilst a multi-stage version of the gear incorporates pistons and rings of the automotive type, the gear pump being located remote from the base. This model is available in single-ram or twin-ram form and may be fitted at the front of the body as well as under the body. The complete range of commercial vehicles is covered by the two types with capacities up to 20 tons.
Latest addition to the range of underbody, front-of-body and slant-type tipping gears produced by Weston Works. (Birmingham), Ltd., Weston Lane, Greet, Birmingham, 1 1 , • is the Twin-Power slant hoist, designed for the Bedford TK chassis, which is also applicable to other popular makes of vehicle. A single type of gear is suitable for Bedford TK chassis of 10 ft., 11 ft. 3 in. and 12 ft. 9 in. wheelbase.
The two rams of the Twin-Power hoist are of the twostage type and are mounted in a robust cradle pivoted in brackets fitted to the chassis frame. Single-ram front-ofbody tipping gears cover lifting capacities of 7 tons to 15 tons, and this also applies to a heavy-duty underbody model for long-wheelbase trucks.
Long-wheelbase Unit
A 7-ton twin-ram slant-type gear and a 10-ton heavy-duty underbody twin-ram model are also included in the range. When a front-of-body gear is applied to a long-wheelbase vehicle, the chassis is equipped with a hinged type of twinframe stabilizer. All gears are supplied with a high-presstire four-cylinder pump.
The Welford company specialize in the production of heavy-duty gear for vehicles in the 10-18-ton capacity range, and although equipment is available for lighter types of vehicle down to 5-ton capacity, proprietary lifting gears are normally employed for vehicles in the medium range. The most suitable type of proprietary pump is fitted, depending on the user's requirements and so on. In a typical case the ram gear is tailor-made in accordance with characteristics of the chassis, weight limitation and the type of operation for which it is intended.
Although proprietary gears are employed by the Eagle Engineering Co., Ltd., Warwick, for many standard applications, the company produces special fipping gears for special purposes tailor-made to match customers' requirements. In the main, these gears are employed for assemblies based on bodywork produced by the, concern. Capacities vary from 10 cwt. to 15 tons in the case of rigid-vehicle bodies and from 11 tons to 15 tons in applications to tipping trailers and semi-trailers.