Chap. XIII.

CARRIAGES I'OR TRAXSPORTIXG WEIGHTS.

1019

waggon.

(2>: t

Fig. 1544. waggon.

Each carriage is provided with a break fastened to the side frame by a cast-iron stud; awrought-iron pin is keyed into this stud, on which the break works, the pin acting as thefulcrum: these breaks or brakes were formerly called convoys, and were made of wood.Waggons of this description carry without heaping55 cwt. of coals. The axles should always be made ofscrap or malleable iron of the best workmanship, of aboutinches in thickness.

Trucks upon four wheels are sometimes used at thecollieries for the conveyance of heavy material; theyare of a simple form, and usually of timber ; the mainframing consists of three longitudinal pieces bolted downupon a timber axle, under which the wrought-iron axlesare secured, upon which the wheels are placed. The

r

—r

a.

.

ii

<>

s>

*

«>

T1

- 1

__

H

Fig. 1545.

Fig.1546.

first cast-iron wheels had their rims case-hardened, wrought-iron tires were then adopted;and some had cast-iron naves, and rims with hollow iron spikes. The wheel now generallyin use is made of wrought-iron entirely, though some have cast-iron rims hooped withwrought-iron; cast-iron is not found sufficiently strong xvhere great speed is required,nor can they be considered safe against accidents.

On some of the northern railways the carriages are more simple in their form, and are soframed that they can be easily taken to pieces : the longitudinal bearers are mortised toreceive the uprights, and the wheels run uponaxles secured to the under side of the trans-verse timbers at the ends. In some cases, by

Fig. 1547.

Railway carriage.

turning a stop on each side, the bottom of thecarriage is made to open and deposit its loadwithout any additional labour. The flanch

Fig. 1548.

PLAN OF CARKtAGB.