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).
Product specification sheet for direct current ampere-hour meters, types NT & NF.
| Identifier | ExFiles\Box 164\3\ img211 | |
| Date | 1st May 1938 | |
| BRITISH SANGAMO COMPANY DIRECT CURRENT AMPERE-HOUR METERS. TYPES NT & NF VEHICLE & BATTERY PATTERN. 2 Wire. THE Sangamo Type NT Meter has been designed for use on all types of Electric Vehicles, from the smallest Electric Truck to the largest type of Electric Lorry. The meter embodies the well-known “Inkwell” principle, which renders a sealing device for the Mercury Chamber unnecessary. The meter loses no mercury during transit, no matter what its position in the packing case may be, and even on the roughest of roads it is impossible for the mercury to splash out of the Mercury Chamber. Its construction and the general details of the mercury motor element, are clearly seen in Fig. 1 overleaf. The base of the meter is of black enamelled cast iron and the cover of black enamelled pressed steel, with an unbreakable glass window. A self-closing aperture is provided for the insertion of the resetting key when necessary, and the whole meter is of extremely robust, dust and moisture-proof construction. All meters are provided with a resistor element or over-charge device, which automatically provides for an excess of charge over discharge. This is adjustable and can be set up to a maximum of 30 per cent. overcharge. A red pointer is provided which can be set to any position on the dial to indicate, for instance, the point at which the battery needs recharging. The pointer can be reset to suit altered conditions, but before doing this it is necessary to remove the meter cover. This pointer is usually set at the desired position before the meter is dispatched. Auxiliary contacts can be provided on the meters as follows:— As a standard fitment, a quick make contact is provided at the zero or full point of the scale. In addition, a similar contact can be provided at the “empty” point, i.e., at the other end of the scale, or at any point between these two positions. Two contacts is the maximum number that can be supplied. These contacts can be supplied as quick break if desired instead of quick make, but in the case of a contact not at either end of the scale it must be specified whether the contact is to make (or break) in the charge or discharge direction. Standard ampere capacities are 30, 40, 60, 80, 100, 150 and 200, and standard dial readings are five times this amount, i.e., 150, 200, 300, etc. The ampere-hour dial reading should usually be approximately equal to 120 per cent. of the ampere-hour capacity of the battery at the ten-hour rate. The Type NF Meter is designed for use in the same way as the Type NT, except that it is intended for Stationary Batteries, although it is often supplied for light Vehicle Batteries. The internal construction of the two types is identical, but whilst the connections of the NT Meter are at the bottom of the meter, the NF Meter is arranged for Switchboard mounting with back connections. SPECIFY WHEN ORDERING. 1. Ampere capacity. 2. Ampere-hour dial reading. 3. Setting point of red hand. 4. Number of contacts. 5. Whether contacts are to be quick make or quick break. 6. If contact required at intermediate point on scale, is this to make (or break) in the “charge” or “discharge” direction. 7. Per cent. overcharge. British Sangamo Co., Ltd., Cambridge Arterial Road, Enfield, Middlesex, England. Sheet B145/0538. | ||