Into the rack j fits the worm wheel k, at the bottom of the shaft of which is a pair of bevel gear wheels l, which are operated by the hand wheel m.

VOL. II.BAND SAW MILL.PLATE XXIII.
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Fig. 3140.
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Fig. 3141.
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Fig. 3142.

A band saw machine constructed by Messrs. London, Berry & Orton, is shown by [Figs. 3140], [3141] and [3142], in [plate XXIII]. The saw-driving wheel d, has wrought iron arms turned true and screwed into the wheel hub. The wooden segments have their grain lengthways of the rim, and between them are placed pieces of soft wood with the grain across the rim. This acts to keep the joints tight, notwithstanding the expansion and contraction of the wood.

The upper wheel is adjusted for straining the saw, and for leading the saw true, by the following construction. It is carried in a U-shaped frame f, which is pivoted at y to a slide that is gibbed to the main frame, and by operating the screw shown at x, the frame f is set to the required level.

To regulate the tension of the saw, the hand wheel k is operated, which drives the pair of bevel gears j and i, the latter of which operates the threaded shaft h, whose upper end g connects with the slide which carries f. Within g is a spring to act as a cushion to the slide, and thus prevent saw breakage should a chip pass between the saw and its driving wheel.

The saw guide frame is secured to the main frame at m′, m′. Upon the face of m, is a slideway for the saw guide arm n, which may thus be adjusted as closely to the upper face of the work as possible.

The weight of arm n is counterbalanced by a rope passing over the pulley v, and supporting the counterbalance weight w. The feed motion is constructed as follows:

On the same shaft as the main fast and loose pulleys a, b, is the feed pulley l, which by belt connection drives pulley m, which is on the shaft w, upon which is a friction disc n, by means of which the rate of feed is regulated. The feed disc n drives the wheel o; the degree of contact between these two (n and o) is regulated by means of the weight t, on the lever u.

On the same shaft as the friction wheel o, is a pinion driving the gear x, which is on the same shaft as the pinion y, which drives the two gears y′ and y′′.

Referring now to [Fig. 3142], gear y′ drives the pair of bevel gears z and z′, for the feed roll e, and the pair of bevel gears shown at z′′, the feed roll f. The gear y′′ drives similar gearing for the feed rolls e′ and f′, seen in the plan [Fig. 3140].