J O U R N A L O F T H E

F R A N K L I N I N S T I T U T E OF THE STATE OF PENNSYLVANIA.

F O R T H E

P R O M O T I O N O F T H E M E C H A N I C A R T S .

%rOL. LXVII.] APRIL, 1874. NO. 4.

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ITEMS AND NOVELTIES, Shaw's Relief Block for Rolling Mil l s . - -At the last meet-

~ng of the Institute, Mr. Thomas Shaw, of Philadelphia, presented the improved mechanism, of which he gave the following description :

The invention, which is here- with illustrated, is designed to prevent the breaking of housings, rolls, and other gearing pertain- ing to rolling mills, and to afford instant relief when the engine is overloaded. In order to fulfil the object mentioned, the demands made upon the invention are pe. cutiar, for it will be observed that the power of a rolling mill is a thing not to be trifled with, that no elasticity is permissable, that the adjustment should be under perfect control, and not liable to disorder when adjusted, and that the parts should be so arranged

Fig. 1. that the operator will be enabled VOL. LXVII.--THIav SmaIl~s,~No. 4.--APRIL, 1874 16

2"22 .Editorial.

to release a load of 500 to 1,000 tons with an ordinary bar wrench, when emergency requires.

All of the foregoing points are met in Mr. Shaw's Relief Bloekr which consists of an obtuse wedge C ~Fig. 1.), supported on the top of its bed.plate A, of corresponding angle. The said bed-plate ter- minates in a flange on its outer end for the reception of the collars o f screw B, which screw is tapped in to base of wedge C, and controls the movements of the same. The wedge C is covered by a top plate D, having side wings, as shown in (Fig 2), reaching down to plate A, to prevent any lateral movement of the three separate parts. The angles of wedge C are made sufficiently obtuse to cause the

wedge to be squeezed outward wheneve r pressure is applied, but the angle shoutd be so acute as not to give any great force to this outward tendency. This angle will vary with the material em- ployed in its construction; witty. steel, three inches to the foot be- ing a sufficient angle for each, side of wedge C. Whenever it~ is desired to withdraw the wedger it is only necessary to apply a~ spanner wrench to the head of ~ screw B, which can be revolved under all loads. This Relief Block is placed in an ordinary housing q (Fig. 8), on top of" the journals of rolls I and H~ and the housing screw .F~ pressed

Fig. 2. upon the top of said Relief Btoek.~ It will be observed how easily this invention accomplishes its task of relieving the screw, rolls, and housings of the severe strain, when metal is caught and locked between the rolls, by using the force of the strain between the journals to eject an obtuse wedge at the will of the operator. The Relief Block is perfectly solid and free from all elasticity, (unlike hydraulic presses tried for the same purpose),~ and will always maintain the height at which they are set, and can, be used for slight adjustments of the rolls when required ; and by in- troducing them, it will no longer be necessary for rolling mill owners,

items and Novelties. 223

to place engines of 50 to 70 per cent. of' excess (~f power~ to crowd through the rolls whatever may be placed between them without regard to the strength of rolls and housings, to the imminent risk of breaking and damaging expensive machi- nery.

All machinery liable to ex- cessive strains should have a limit of safety before its maxi- mum strength is reached. Ir~ rolling mills, this engine is the best safety-valve for over- strain, which should be so pro- portioned with steam, as to stop the engine before break- ing the machinery.

There need be no fear of the engine slacking up under or- dinary work, for the damag- ing strain is from 50 to 100 per cent. in excess of ordinary loads. Whenever the engine

:Fig. 3. slacks speed from excessive strain, liable to break the machinery, instant relief can be afforded by the Relief Block here described.

C o a l - c u t t i n g M a c h i n e r y . * - - A n exhaustive treatment of the subject of coal-cutting by machinery, and its probable influence on the future of coal mining industry, was lately had before the Cleve- land Institute of Engineers~ Middlesbrough~ England. The conclu- sions derived from this discussion are stated to have been taken from the best results of the best machines yet invented. This distinction seems to have been accorded without dispute to the so-called Gart- sherrie coal-cutter of the M~essrs. Baird~ which has been in operation constantly at several large collieries ever since its first introduction, some six or seven years ago. The advantages claimed for this ma- chine are :--1, a diminished cost of production ; 27 an improved yen-

American Exchange and Review, April, 1874.