Speed indicator having 2 3/8th” printed dial, with dual concentric scales calibrated in revolutions per minute, the inner scale reading from 0 – 2,500 RPM, the outer from 2,000 – 10,000 RPM. The upper dial with maker’s logo, “Elliott,” and annotated “Speed Indicator” with serial “No 17508,” the lower part signed by the maker “Elliott Brothers (London) Ltd.” Japanned pointer set beneath a bevelled glass maintained in a heavy bezel with screw thread and locking pin.
The elongated drum form case with twin-drive chronometric movement, marked to the case “500 – 2,500” and “2,000 – 10,000,” a warning engraved adjacent to the couplings states, “See that adaptor is on correct range.” The instrument together with a full set of accessories including: flexible drive coupling, three separate drive bits, 1¼” pulley, original drive cord and oil bottle. The instrument instruction booklet stowed at the front of the case with heavy blue canvass backing and entitled “Directions for using Elliott Portable Speed Indicator,” the header with instrument serial “No. 17508.”
All contained within the original lacquered mahogany case, nickel plated hinges and spring safety latch, finger jointed corners, the lid top and case bottom secured with brass slotted screws. The inner lid with purple velvet faced pad.
This type of rotary speed indicator, patented in 1881, was designed by Young, a naval engineer. It is a portable instrument for use with any rotating machinery; in use it is held against the rotating shaft using one of the adaptors supplied with the instrument.
With two speed ranges the instrument is coupled via the flexible drive to one or other of the input shafts, it is important to know roughly what speed range the item to be measured operates at in order that the correct input is chosen, ie between 0 and 2,500 RPM or 2,000 and 10,000 RPM. The supplied pulley, if appropriate, is fitted directly to the chosen input, a piece of cord cut to the correct length, passed around the item to be measured and tied off so as to form a short belt.
In good working order, this instrument remains in entirely original and complete condition: some signs of use especially to drive bits, the instruction booklet with some damage to edge, the case with general light marking and abrasions.
Although not uncommon, these very collected instruments are very difficult to find in such complete and original condition – the vast majority lack the instruction booklet and many have missing accessories.
Dimensions: 4½” wide x 4″ high x 4″ deep (case)
Stock No: SI0471