Trials of Traction-Eitf/iiies at Wolverhampton. 
539 
to extcml bcliiiul tlio fire-box far enough to receive the second-motion sliaft- 
bushes. The spnr-pinion on the riijht-hand end of the secoud-motiou shaft 
gears into a spur-wheel, which runs loose upon tlic axle of the drivin<;-\vbeels, 
and carries in itself two bevel-pinions, which gear into two bevel-wheels, the 
left-hand one keyed fast on the driving axle, the ri;4ht-hand one attached to 
the riglit-haud driving-wheel boss, which runs loose upon the axle. The left- 
hand driving-wheel is also loose upon the axle, but can be attached thereto by 
a pin, which slides through its boss and fits into one of four recesses provided 
in the break-wheel, whicli is keyed fast on the driving-axle, at the left-hand 
side of the fire-box. 
Those who arc conversant with some of the traction-engines that have been 
made of late years, and, still more, those who are conversant with cotton- 
sinuning machinery, will see that the drivmg power is applied to the two 
wheels by means of what is now, and properly, called a compensating motion, 
but which in cotton-spinning machinery is known as the " Jack-in-the-Box." 
While going along a straight road the bevel-pinions act as mere fixed drivers 
to the right and left-hand bevel-wheels, and have no motion of rotation round 
their own axes ; but should the steering require the engine to make a curve, so 
that the wheel on the outer side must traverse a greater space than the wheel 
on the inner side of the curve, then the pinions begin to revolve about their 
axes to such an extent as to compensate for this difference of motion. Several 
makers have applied the compensating motion to traction-engines before, but 
they have been tempted to abandon it, because if one wheel gets into a slippery 
hole while the other remains on comparatively firm ground, there is a liability 
that the energy of the engine would be spent in driving the wheel in the 
slippery hole, instead of the wheel upon the firm ground. Mr. Aveling, however, 
says he finds the convenience for general work in this compensating arrange- 
ment so great, that he prefers to irse it, putting in spikes to the wheel which 
may be in the hole, and thus giving an abutment for the motion to work upon. 
Further on, when we relate the trials which took place upon the high road 
it will be found that the use of the jack-in-the-box did give occasion under the 
most severe load for one wheel to run round while the other stood still. We 
should recommend to the ingenuity of Messrs. Aveling and Porter, and to that 
of the other exhibitors, the solution of the problem how, without complication or 
expense, to arrange a motion by which the jack-in-the-box might at will 
be thrown out of gear, so as temporarily to drive the wheel by a rigid connection. 
It may be as well here to state that the driving-wheels, which are 6 feet 
in diameter, and 1 foot 6 inches wide, have cast-iron rims, made with a sort 
of cellular pattern, to work upon the road, and are each provided with seven 
pairs of holes, to receive either spikes or the pins by which pieces of angle- 
iron, called paddles, are bolted across the faces of the wheels. The steering- 
wheels have also cast-iron rims, with a fillet upon them to prevent their slipping 
sideways when traversing " side-long " ground. They are carried on a fixed 
wrought axle attached to the under-side of a wooden bed. A perch-pin passes 
through the axle, through this bed, and through a wrought bracket formed on 
the bottom of the smoke-box and barrel. The lower end of the pin is stayed 
in the ordinary way, as in portable engines, by a stay-rod, which extends 
back to the front of the fire-box. To the outer ends of the wooden bed two 
chains are attached, whicli are led away to an axle carried in brackets at the 
front of the fire-box, around which they are wrapped in contrary directions. 
On the right hand of the axle there is a worm-wheel, driven by a worm-pinion, 
fixed on the lower end of an inclined shaft, the other end being within easy 
reach of the driver as he stands on the foot-plate of the engine behind the fire- 
box. He has also close to his hand the reversing handle, the steam-regulator, 
the ash-pan damper-handle, and the brake-handle. The feed-pump regulating 
cock is also close to him ; and thus one man, or, in fact, one boy, can with the 
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