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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Tensile and vibration tests of bolts fitted with 'Perfloc' nuts.

Identifier  ExFiles\Box 77\5\  scan0219
Date  19th April 1912
  
14 Old Queen Street,
Westminster, S.W.
19th day of April 1912.

Report on Tensile Tests of Two 1" Bolts fitted with 'Perfloc' nuts and Vibration Test on one 3/4" 'Perfloc' nut.
Received from the Engineering Improvement Co Ld.
Received 1st April. Tested 19th April.

| Test Number. | Marks | Dimensions of Bolt (Breadth Inches, Thickness Inches, Area Sq. Inches) | Limit of Elasticity (Yield Point) (Pounds, Tons Per Sq. inch) | Breaking Load (Pounds, Tons Per Sq. inch) | Ratio of Limit to Break | Extension on whole length of | Reduction of Area at Fracture per cent. | Work of fracture in Inch tons per Cubic Inch (calculated) | Remarks. |
|---|---|---|---|---|---|---|---|---|---|
| 35130 | None (1" Steel Bolt bright all over as received) | 1.002 diam; 0.7885 At bottom of thread 0.845 diam; 0.5608 | 39,140, 17.48 | 61,650, 27.53 | 0.635 | 4.0 (not including fracture) | - | - | Bolt broke three threads distant from outside of nut; fracture granular. Nut unaffected. |
| 35131 | None (1" Steel Bolt turned down to bottom of thread) | 0.845 diam; 0.5608 | 39,140, 17.48 | 56,220, 25.10 | 0.696 | 43.7 (including fracture) | 68.14 | - | Bolt broke in parallel part; fracture finely granular, silky at edge; cup fracture. Nut unaffected. |
| 35155 | None | Four plates 7/8", 1/4", 3/8", and 3/8" thick respectively, were bolted together by two 3/4" bolts, 6" apart. One bolt had 'Perfloc' nut, the other an ordinary nut, fairly tight fit. Both nuts were tightened hard up so that spring was taken out of plates. 30 blows with a 10.lb hammer made no difference. Both nuts were then slacked back to allow some spring in plates, and a plain nut jammed down on ordinary nut to lock it. The ordinary nut was tightened up twice during 35 blows, made in order to take out bend of plates. Finally a further 35 blows slackened the ordinary nut, but did not affect the 'Perfloc' nut in any way. | | | | | | | |

The Secretary,
The Engineering Improvement Co Ld,
39, St James' Street, S.W.

(Signed) Burstall & Monkhouse.
  
  


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