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).
Design review and critique of hydraulic shock dampers, with annotated diagrams.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan094 | |
| Date | 3rd April 1931 | |
| DA{Bernard Day - Chassis Design}/HDY.{William Hardy} ) FROM R.{Sir Henry Royce} HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} ) (At Le CanadelHenry Royce's French residence.) ORIGINAL R2/M3.4.31. x235. HYDRAULIC SHOCK DAMPERS. We have still not mastered this design to promise lasting satisfaction and ease of manufacture. (1) I cannot see how you can easily cast the pistons. [Annotation for upper diagram, left side] But undercut prevents it. [Annotation for upper diagram, right side] Recess here suggests vertical moulding which is economical. [Annotation for middle diagram, left side] Would get flats in turning if impossible to cast small enough. [Annotation for middle diagram, right side] To make a practical job this tapping should be smaller, not more than 3/8". Perhaps you intended die cast aluminium bronze but I think my round bosses from the 3/4" thick (recessed) piston head is simple & light. (2) The second point is that you have so many places to trap air - i.e. each end of cyl. and the valve chamber in the piston. If you want to use the oil passage that lubricates the bearing to carry away air it is quite OK. The bearing will not mind the air in the oil. (3) The two hexagon headed plugs for the main valve are wrong, being too close together for box key. I prefer the type of head with collar that does not get its face damaged. (4) More air locked spaces in main valve passages. [Annotation for lower diagram, left side] Round boss gets flatted. [Annotation for lower diagram, middle] Dia. of stem to pad .3125" ball .3000". [Annotation for lower diagram, right side] Drill above & below for air and dirt. Smaller screw - i.e. 3/8" or less. (5) Would it be better to make the replace valves same as release valves come out better with screws - i.e. better to handle (perhaps) - probably ball less sluggish. If valve had stem it could go right through. Try both. I think the leak past valve should be in valve so that it can be examined, or in screw, but the very simplest to drill one valve. Valves better not interchangeable, or if mixed they may affect clearances unless all valves exactly alike. I do not like the leak a small hole in main casting that cannot be cleaned. R.{Sir Henry Royce} | ||