DUNLOP-FERGUSON ANTI-SKID BRAKING CONTROL SYSTEMAS FITTED TU JENSEN 'FF'

One of the outstanding features of the newlyannounced Jensen 'FF' (Ferguson Formula)saloonis the incorporation of the Dunlop - Ferguson

anti - skid braking control system in this radical

four -wheel-drive model. Jensen are the firstmanufacture r to offe r a production car with thisbraking system. Not only does its use resistwheel -lock, but i tals 0 inc reas e s drive r controland directional stability during heavy braking.

Development.

The Dunlop r r Maxaret r r anti - skid unitwas first made available to the aircraft industryin 1952, and was developed to ensure that optimumbraking power can be applied in all conditions ofweather and runway, without wheel-lock and skidd­ing resulting. This unit, consisting of a spring­loaded flywheel linked with each of the aircraft' slanding wheels, senses the rate of wheel decel­eration and reduces braking pressure at the pointwhere an increase in the deceleration rate wouldinduce wheel-lock. The resulting increase in theforward speed of the wheel is sensed by the "Max­aret", which then causes the brake pressure to becorres pondingly inc reas ed. Completely automaticin operation, this ingenious device leaves the pilotfree to concentrate on the other aspects of his lan­ding run, and has proved enormously successful in

"Maxaret" unit "in situ"

service on many civil and military aircraft.Ferguson engineers, in developing their adv­

anced 'Ferguson Fo;rmula ' 4-wheel-drive system,found the answer to the problem of safe brakingonthe road with this device, the uses of which Dunlopwere extending to road vehicles following its succ­ess with aircraft.

Tests carried out by Dunlop and the Road ResearchLaboratory in 1958, using "Maxaret" units on allfour wheels of a conventional front - engine - rear­wheel - drive car, provided convincing proof of thecapabilities ofthe "Maxaret": during heavy brakinga marked increase in both directional stability andcontrollability was achieved. More recent tests bythe Road Research Laboratory illustrate the rem­arkable effectiveness of the "Maxaret" system inthe form adopted by Ferguson: (stopping distancefrom 45 mph under EMRGENCY BRAKING on thesame test surface).

1. Ave rage of a number of conventional road vehicles:220 ft (all wheels locked)

2. Ferguson prototype with "Maxaret":149 ft (no wheels locked)

SAVING IN STOPPING DIST ANCE B Y FERGUSONWITH "MAXARET": 71 ft.

Shown here are the servo mastercylinder assemb/y and servo contro/ va/ve.

The 4- wheel- drive car wi th no wheels lockedwas always completely under control and could be

steered to safety.

With the development of the Ferguson 4-wheei­drive system it was found possible to combine theanti- skid advantages de ri ved from the Fe rgusonsystem and its "master" centre differential withthe advantages derived from the Dunlop "Maxaret"anti- skid unit using only one "Maxaret" unit.

This was possible because the differentialitself makes 'it impossible for the front or rearpairof wheels to lock separately, and, if front and rearwheels tend to lock together, the single "Maxaret"will at once come into operation and momentarily

relieve the brake preesure on all wheels. This

takes place without" spilling" any of the fluid in thehydraulic braking system because, in the Fergusondesign, the "Maxaret l' unit, which normally releas­es brake fluid, does not operate on the brakes themselves but only on the vacuum servo unit.

The Dunlop - Ferguson anti - skid brakingcontrol system as developed for the Jensen I FF'is not at present available for cars with conven­tional dri ve layouts, but the' I Maxaret ' I is being inten­

sively developed for othe r vehicle applications­such as articulated commercial vehicles where itoffers an effective solution to the problem of "jack­knifing".

ENGINE INDUCTIONMANIFOLD

SERVO MASTER CYLINDERASSEMBLY

VACUUMRESERVOI R

MAXARET

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SWITCH =l}==d

II

IIL

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SERVO CONTROLVALVE

FRONT BRA!(ES REAR BMKES

= SERVO CONTROLL1NES

~ HYDMULIC L1NES

ELECTRICALCONNECTIONS

DUNLOP RUBBER CO. LTD.,ENGINEERING COMPONENTS UNIT,FOLESHILL,COVENTRY.