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.:oupling and landing gear

2nd December 1966, Page 139
2nd December 1966
Page 139
Page 138
Page 140
Page 139, 2nd December 1966 — .:oupling and landing gear
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AS the nation turns increasingly to the road vehicle as a means of providing its overlai transport so the transport industry is gradually turning to articulation which provid the greatest flexibility in a haulage fleet. Changes in the C and U Regulations have given ti articulated machine the edge on its rigid counterpart with regard to carrying capacity, and ti fact that a tractive unit can be called upon to perform many different duties, simply by couplii it to a specialist semi-trailer, gives the haulier opportunity to create an extremely efficie service for his customer.

Much work has been carried out by the vehicle and semi-trailer builders to make tl articulated vehicle safer on the roads, and more efficient in its operation. But a section of ti industry that has been given little publicity over recent years is that which provides that a important link in articulation, the coupling and landing gear.

A full-length article could be written on each type of gear produced by each maker lat on this occasion, we shall look at the subject with a view to finding out where the units a made and what ranges are in fact available. As will be seen, most of the equipment is nm by trailer manufacturers.


Baden Trailers Ltd., Royton, Oldham, Lancs.

ENDING gear is manufactured by this

company and comprises a pair of tubular assemblies within which there is an inverted screw and nut. The nut, which is of phosphor bronze, is carried at the lowest extremity of a revolving tube, turned through a bevel gear-train at the top of the casing. Taper-roller thrust bearings carry the load and the whole of the working parts of the screw gear are immersed in oil.

The brake lever in the centre of the king pin BTC is retained for the secondary braking system. British Trailer Co. Ltd., Phoenix Works,

Richmond Road, Trafford Park, Manchester.

THE main feature of the fifth-wheel coupling

made by this company is the traction shockabsorbing unit that it incorporates. This takes the form of spring-loaded mounting trunnions which are carried in mounting boxes. These boxes are machined inside to accept the trunnion blocks. Four heavy-duty coil springs are housed, two in each end of the trunnion block. When the unit is assembled the springs are compressed and the block inserted into the carrier. It will be seen that by this method the longitudinal oscillating pivot point of the fifth-wheel is located in a springloaded manner, there being no direct transmission of traction, or overrun-shocks from trailer to tractive unit or vice versa.

The coupling has a fully machined surface and incorporates in its jaw mechanism two interesting features. The first of these is that the unit designed to lock on the largest of the king p diameters and not on the 2in. shoulder used other types. It is claimed that because this poi is nearer to the root of the pin it has inherent greater strength. The second point is that tl locking jaws always return to the closed positic irrespective of the unit being coupled or uncouplc Thus it is impossible for a mistake to be mac when coupling for the unit can only lock itsel it cannot under any circumstances release withol the mechanism being manually operated.

The company also produces a convertt coupling which permits tractive units havir, automatic-type couplings to be coupled to sem trailers with the SAE/SMMT fifth-wheel type.

A king pin to SAE/SMMT standards is main factured from a 73-ton tensile drop-forging an special mounting frames for the fifth-who are also produced. This is normally made froi rolled-steel channel and it incorporates Ion lead-up ramps which facilitate easy coupling t trailers with varying rubbing plate heights. Th coupling is suitable for operation at up to 38 tor g.v.w. and weighs 3.5 cwt. The mounting fram weighs on average 0.5 cwt.


J. Brockhouse and Co. Ltd., Wheeled Vehicles Division, Victoria Works, Hill Top, West Bromwich, Staffs.

AN automatic roller-type coupling conformin to the SMMT standard and being completel interchangeable with all other makes of this typ is made by this firm.

The model follows closely the design of othe makes and incorporates safety features in th coupling and braking systems. The coupluij hooks are hydraulically retracted for releasinj the trailer and tractive unit, and semi-traile braking systems are matched through a syn chronizing reaction valve. The semi-traila portion of the coupling is designed to eliminatt the possibility of the undercarriage collapsing when coupling and uncoupling are taking place.


Carrimore Six Wheelers Ltd., North Finchley, London N12.

A WIDE range of couplings is made by thii

company and among them are one or twc that are very unusual. Some models are intender for applications where vehicles are continually uncoupled and others for those where that it not the case.

The standard SAE/SMMT fifth-wheel coupling is of pressed steel construction incorporating it mechanical and spring-loaded locking chanisms. This model is interchangeable with SMMT-standard semi-trailers.

A permanently coupled type of unit is winced for use on vehicles that never need be separated and this comprises a gimbal ;embly with the lower half of the gimbal :d to the tractive-unit chassis and the king pin punted on the top half. The turntable is fitted the semi-trailer. The Quickfit is a fixed-rampie coupling which incorporates self-coupling ike pipes and automatic locking gear. It can ly be used with trailers equipped with the propriate top half.

The most complicated unit produced is the etractor which although originally designed to nprove the appearance of the articulated vehicle, as been found to eliminate jack-knifing. This nit has the effect of lengthening the king pin rear axle dimension when the tractive unit ad semi-trailer are set at an angle to each other.

this way the body-to-back-of-cab dimension an be substantially decreased without resorting excessive bow-fronting of the trailer bodywork, ad as the vehicle turns the BBC dimension pens up to provide the necessary clearance.


:rane Fruehauf Trailers Ltd., South Green Yorks, Dereham, Norfolk.

rHIS company offers a range of fifth-wheel couplings covering imposed loadings of up to 5 tons. All the units in the range are of pressedtee fabricated construction and offer certain .dvantages with regard to weight. There are our basic models, the two heaviest produced ither with fore and aft oscillation only or with niversal oscillation for use in rough conditions. 'he lowest-rated unit, the MR14, will accept mposed loads of up to 14 tons and weighs .36 lb. The highest-rated unit is the HR35 which iceepts imposed loads of up to 35 tons and in its niversal-oscillating form weighs 881 lb.

One of the features of the couplings is visual means of ascertaining that the jaws are correctly locked for operation. The mechanism is simple and robust providing for quick and simple overhaul. The locking jaws engage on both the king pin diameters so providing a larger area over which the working loads can be spread.

Landing gear offered by the company is of fabricated steel construction incorporating a reduction gearbox. With this unit in low gear the legs will lift 22 tons. In high gear the assembly gives a lift of I in. to every two turns of the operating handle. As the support tubes are of square section the need for a lateral tie between the landing feet or wheels is obviated so providing for greater clearance over obstacles.

Other coupling gear offered by Crane Fruehauf is confined to upper fifth wheel rubbing plates for mounting on tankers or frameless van designs. These are available with angled leading edges and with king pins either bolted or welded into position.

A sliding mounting is produced by the company giving a range of adjustment fore and aft of 18 in.


Davies Magnet Works Ltd., Thundridge, Nt. Ware, Herts.

FOURTEEN different types of fifth-wheel

couplings are offered by this company which is probably the largest manufacturer of coupling and landing gear in the UK. The range of landing gears includes six different models.

All fifth-wheel couplings made incorporate the same basic specifications of double-safety jaw locks and robust construction. Capacities range from the lightest model, the 215, at 6,000 lb. superimposed, 6,000 lb. tractive, to the heaviest. the 530 and 600 models, at 76,000 lb. imposed and 64,000 lb. tractive. Throughout the range, units can be supplied with either longitudinal oscillation only for roadgoing applications or with universal oscillation for rough conditions. The heaviest unit in the range is the 530 which has a 36-in.-wide plate, is universally oscillated, stands 12.125 in. high from base plate to fifth-wheel surface and weighs 656 lb. The lightest in the range is the 215 which has a 15-in, wide plate, is universally oscillated, 5.562 in. high, has a single coupling-jaw and weighs 66 lb. This unit accepts a 1-in.diameter king pin. Other models in the range conform to the two SAE and SMMT standards 37 and 55.

King pins are produced from a heat-treated EN 16T steel giving a high degree of resistance to wear.

The six landing gears made cover a range of loadings from 5,000 lb. up to 54,000 lb. These units are produced in cast steel, high-tensile light-alloy, or from steel fabrications. The shortest extension of the legs is on the fabricatedsteel VG 460 model at 11 in. This unit carries a rating of 5,000 lb. The greatest extension is on the fabricated steel model VG 448 at 17 in. The loading here is 44,800 lb.

All these units can be supplied with a variety of foot mountings, either wheeled or with elephant feet. A range of gearboxes available with ratios of 1 to 2, 2 to 1, or 1 to 3 and 11 to I.

Two basic types of internal screw gear are used in the units, one having the jack-screw fixed and the nut running free at the top of the leg, and the other with the nut fixed at the bottom of the leg and the screw turning. The latter type has the advantage in that the actual point of contact between nut and screw is always submerged in oil.


R. A. Dyson and Co., Ltd., Grafton Street, Liverpool.

NO fifth-wheel landing gears or couplings are marketed by this company, but it does carry out conversions to proprietary couplings making them into sliding units. These are often mounted upon heavy-duty tractive units designed for use with numerous different types of machinery carriers and the like.

The company does, however, offer special types of folding king pin for use on TIR semitrailers and other types which must couple to various types of tractive unit.


Hands (Letchworth) Ltd., Letchworth, Herts.

A UTOMATIC couplings ranging from 3 to '12 tons capacity are manufactured by this company and are available for all types of prime mover. The main features of these couplings, which are made in two sizes-3 to 5 tons and 6 to 12 tons—are the coupling arrangments and the generous turntable dimensions they incorporate. Coupling is effected by two largedimension coupling hooks which lock by an overcentre pawl around the ramp rollers of rampand-roller-type automatic coupling. The landing gear sections of the couplings are mounted on the semi-trailer and here the turntable of 19 in. diameter adds considerably to the general stability of this type of unit. Other safety features are spring-loaded brake gear which in the event

of a trailer breaking away from the tractive unit automatically applies the semi-trailer brakes, and a non-collapsible undercarriage.

A fabricated-steel fifth-wheel type coupling is made and this has an imposed load capacity of 9.5 tons. This unit is of the rubber-mounted trunnion variety and it incorporates the Hands locking gear which is claimed to be extremely efficient. In this design the king pin is locked in the fifth-wheel by a single jaw which locates around the pin across the opening of the lead-up ramps. It is retained in the locked position by an over-centre pawl and has the advantage of being a single-piece unit against the normal twopiece jaw assembly. A new version of this unit, shortly to be announced, will have an imposed load capacity of up to 11.5 tons.

Rubbing plate and king pin assemblies are produced by this company either for application to standard semi-trailers or as a unit for mounting on tankers and other bulk carriers. The king pin in all cases is of the bolted-in variety.


Primrose Group Sales, Ewood, Blackburn, Lancs.

A LLOY steel jaws of 100 tons tensile strength 'are used in the fabricated-steel fifth-wheel coupling manufactured by this company. The unit is longitudinally oscillated and is fabricated from 0.25 in. steel plate superimposed upon a 0.5 in. saddle plate and ribbed both transversely and longitudinally with 0.625 in. electrically welded stiffeners.

A simple locking mechanism is provided which needs manual operation for releasing only. Recoupling is automatic once the tractive unit is pushed back beneath the semi-trailer.


Scammell Lorries Ltd., Tolpits Lane, Watford, Herts.

A WIDE range of automatic and fifth-wheel

couplings is available from this company. In addition to standard models there is also a converter unit which allows fifth-wheel semitrailers to be matched with tractive units having automatic couplings.

A new automatic coupling is now produced and this bears the name Supersafe Mark III. Following closely the pattern set by the Scammell MH coupling which has been made for many years, the Supersafe embodies new safety features. The landing gear is now non-collapsible and the rocking beam is replaced with a fixed beam which ensures interal stability when cornering. The method of fitting the coupling remains the same in that there are two split collets which nest in a groove around the top of the coupling king pin, with the actual turntable plate being attached by a number of studs. New regulations have made the through-the-coupling braking system obsolete as far as service braking is concerned, but the linkage is retained for the purpose of a secondary braking system for which it will produce adequate retardation. This type of gear is suitable for use at weights of up to 12 tons g.v.w.

With the distinction of being the only one of its kind offered by any company, the Scammell heavy-duty automatic coupling gear brings to the heavier outfit the quick change characteristics of the "Mechanical Horse". This unit was first shown at the Commercial Motor Show of 1954 and is suitable for operation at up to 24 tons g.v.w. The actual coupling gear is a heavier version of the MH coupling without the landing gear section. The landing gear comprises a pair of pneumatically powered legs which can be controlled from the driving seat.

SMMT-type fifth-wheel couplings are produced in two capacities—for 7 tons imposed load and 12 tons imposed load—being suitable for operation at 24 and 36 tons g.v.w. These units are of high-grade cast steel embodying double locking jaws and a grouped lubrication system. The plate oscillates through phosphor bronze bushes and the complete unit weighs 3.25 cwts.

For semi-permanent outfits where there is little likelihood of tractive unit and trailer being separated except on the odd occasion, Scammell produce the Spherub coupling. This comprises a cast steel turntable mounted on rubber but with its movement restricted by steel stops. The top half of the coupling takes the form of a steel pressing, and a dolly-spindle passing through the centre of the king pin operates the trailer brakes.

The converter unit is a fifth wheel mounted upon an automatic-coupling roller beam allowing the fifth wheel to be superimposed on a tractive unit fitted with automatic coupling gear, when it will be able to handle fifth-wheel type semi

Quickly adjustable king pins are supplied a the system used is simple and easy to use. 1 locking bar is slid forward releasing both I king pins. The driver then selects the one he wal to use. When this is done the lock is returned its original position and the trailer is coupled the normal manner. Rubbing plates with tl device installed are produced and give pin po tions with 30and 42-in. overhangs.


Taskers of Andover (1932) Ltd;, Anna Valley, Andover, Hants.

AUTOMATIC couplings with capacities from 3 to 12 tons are made by Taskers, well as a fabricated fifth-wheel-type unit.

The automatics are known by the name Double Safety and incorporate double locks ai a non-collapsible undercarriage. There are tl og everything that matters in this equipmer and generously proportioned turntables assi in producing general vehicle stability.

The turntables are so designed that entry foreign substances between the rubbing surfac, is eliminated. The inclusion of a graphite fabric disc, which requires no attention, red= maintenance time. Coupling mechanism operated by vacuum or air servos. Both the uni in the range-3 to 5 tons and 6 to 12 tons—a fully interchangeable with other roller-tyi automatics.

Two fabricated fifth-wheel-type couplings a produced, one for operation with semi-traile up to 25 tons capacity and the other for uni over 25 tons. The first-mentioned is for use wi the standard SMMT 2in. king pin; the seem with 3.5in. diameter pin is for use on heal machinery carriers. The approximate weight the latter unit is 4.75 cwt. including the subfran mounting.

Slipper plate and king pin assemblies a made and these utilize a close-fitted socket type pin and not the usual bolted or welde flange-type unit. The pin is mounted in a dee block providing adequate safety margins for a forms of operation.


York Trailer Co., Ltd., St. Marks Road, Corby, Northants.

'THREE variations of a pressed-steel fiftl -A wheel coupling are offered by York Trailer: The unit is called the Big D and the top plate ] formed from one complete pressing. The long tudinal oscillation trunnions are carried in rubbe bushes which insulate heavy shocks from th chassis frame. The plate can be supplied wit trunnion brackets of varying heights, the lowef giving an overall height from the frame top c 7.5in., and the highest giving an overall heigt of 10.25in. The plate is claimed to provide bigger bearing surface than other types and th jaw locking mechanism provides positive securit once the pin has been pushed home. There i simple adjustment to take up the slack as th jaws and pin develop wear.

The unit is also provided with a sliding sub frame enabling speedy adjustment of axle loading and vehicle length. This allows for movemen over a distance of 12in. in increments of 3M giving four positions.

The third style of this coupling is as a con verter unit. In this form it bears the name of Yorkamatic, and it is mounted upon a pair of automatic coupling rollers and has the necessary locking gear beneath the plate.

In standard form the Big D coupling weighf 3501b. complete with mounting plate. With the sliding mounting it weighs 4261b., and as a con verter unit 2501b. R.D.C.


People: Victoria Works

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