THE AUTOCAR El Journal publisheb in the interests of the mechanicall\? propelleb roab carriage.

EDITED BY H. WALTER STANEq.

No. 673. VoL. XXI.] SATURDAY, SEPTEMBER 12TH, 1908. [PRICE 3D.

The Autocar.

(Published Weekly.)

Registered as a newspaper for transmission in the United Kingdom.

Entered as second.class matter in the New York (N.Y. ) Post Office.

Editorial Office :

COVENTRY.

Pub[;shing Offices :

20, TUDOR STREET, LONDON, E.C., England.

CONTENTS. NOTES

USEFUL HINTS AND TIPS . •

THE ROYAL AUTOMOBILE CLUB AT NORWICH {]LLUSTRATED)

THE 15 H .P. FOUR-CYLINDER ZEDEL (ILLUSTRATED)

THE FOUR I NCH RACE IN THE ISLE OF MAN • •

u THE AUTOCAR .. MOTOR CAR LECTUR ES • •

TALBOT MANAGEMENT CHANGE

Bv MOTOR ACROSS AUSTRALIA (ILLUSTRATED )

PAGE

. . 391-392

393 394-398 . . 399-401

AUTOMOBILE ENGINEERING AT THE B IRMINGHA:'\I UNIVERSITY . .

A COLONIAL TOURING C AR (ILLUSTRATED)

THE FLORIO CUP RACI-'. ITALTAN S UCCESS • •

406

406

CoRRESPONDENCE • •

ON THE RoAD. IN WALES. Bv OwEN JOHN

CoNTINENTAL NOTES

FLASHES • ,

. . 4II-41 5

416-417

418

THE CAUSE AND PREVENTION OF WEAR

Subscription Rates :

British Isles, 16s. Abroad (thin paper editio~). 22s. 8d. per annum.

( Notes. Differential Locking. Among the many side-slip preventing devices for motor cars which have been brought out from time to time we do not remember anv means to provide for the locking of the diffe~ential. Our· atten­ tion has again been drawn to the matter by Motor Traction, which recently published the regu­ lations laid down by the War Office for their light tractor competition. One of the conditions requires that on all the machines entered for this competition p rovision should be made for rapidly locking together each pair of driving wheels , the locking arrangement to be capable of manipulation from the footpl ate by the drive r. Of course, this provision, so far as the War Office is con ce:-ned, is not made with the idea of ore­ venting side-s lip, but rather to give th e tractors - thP ability to pull out of very uneven, steep , or gre,1-.·, places. As it is , practically all traction engines are made with an arrangement for locking the differential , but this can only be put into action by stopping the engine and inserting a stout pin into the boss of one of the driving wheei s.

\ Ve recognise a t once that ·any arrangement. for ]~king the differential on a car capable of fairly high speeds must be of a very simple, reliable, and "foolproof " character, as if it were misused in any way or likeh· to come into action unexpectedly it would be a source of the very gravest danger. On the other hand, there is no doubt whatever that there are possibilities in the idea, old though it is. It would not only be ve ry useful for restarting up a greasy hill , but it would undoubtedly se rve to prevent side-slip in many cases, though improperly used it would tend to increase it. It is a matter which has not received the attention from inventors which it deserves, and we moot it as a subject to which they might direct their thoughts with advantage.

The Defects of the Differential. A few years ago the differential was a constant source of anxiety to the motorist, as it frequently went wrong, its commonest defect being the seizing of its bearing5 or the breakage of its pinions. These objections have long since been overcome by improved . design_ an_d superior material, but for all that the d1fferent1al 1s not an entire ly satisfactory part of a motor car, and it never will be while it works on its present principle. As has often been indicated, its defect from a motor car point of view is that it differentiates to resistai:ice instead of to distance so that when one wheel shps on greasy ground the ~ther one cannot do anything to help its fellow, as the wheel 0 :1 dry ground er comparatively good holding surface become , as it were, an anchorage for one- half of the differential, -and the consequence is that the wheel on the grea5y surface continues to spin without driving the ca r forward . It would often be a great convenience, especially in the limestone districts in the winter tim e, if the two wheels could be locked together till a fair start had been made, but this is only a makeshift arrangement after all.

What we really w;.int is something which will practica l!\· ah,·a,·s lock the two 1rheels when the car i5 pro ceed i~g in a straight line . :rnd 11·hi ch will automatically release the inner wheel when it is describing a curve . On drv ground the balance gea r does better than this , as it drives both wheels in the proper degree for the varyi ng distances th ey are covering , but it fails directly adhesion is insufficient , and if one wheel slip5 the other does not help it to maintain the d riv e. This is not merelv an ji{com·enience when cl imbing steep greasy place~ . but it indirectly produces sirle-slip. because a dri,·ing wheel which is revolving without biting the road is practically a wheel ,,·hich has lost its sense of dire,t io n. In other 11·ords, a wheel which is slipping round and round has lost its grip of the road, and is a ll rea dv to s li p sideways, and it often does so slip. Another ohiection to the diffe renti al is that when th e differential ·brake is app lied on a grea~~- road the ten-