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).
Specification sheet for 'Syncarbon' brush grades detailing their properties and applications.
| Identifier | ExFiles\Box 166\1\ img110 | |
| Date | 11th July 1938 guessed | |
| SYNTHETIC CARBON & ENGINEERING COMPANY, LTD. Cumberland Road, Stanmore, Middlesex. Telephone: Wordsworth 1240. Telegrams: Syncarbon, Stanmore. SPHERE OF USE OF “SYNCARBON” BRUSHES Main Carbon Brush Grades and their Application. Hard Carbon Brush Grades. Normal pressure 2½ lbs. per sq. inch. Grade | Spec. Res. Ohms per Inch Cube | Coefft. of Friction | Contact drop at Normal Current Density volt | Approx. Maximum Commutator Speed Ft. per Min. | Normal Current Density, Amps per sq. in. (Commr.) | Application and Characteristics SC3 | 0·0019 | 0·28 | 1·2 | 3000 | 40 | Special grade for small motors such as fan motors, vacuum cleaners, etc., with flush mica. SC1 | 0·0018 | 0·27 | 1·18 | 3000 | 40 | Hard Carbon Brush for DC and AC commutator machines, also used for switch contacts. SC8 | 0022 | 0·14 | 0·9 | 4000 | 55 | Medium hard Carbon. Suitable for machines with flush soft mica. Hard Graphitic Brush Grades. Normal pressure 2-3 lbs. per sq. inch. SP{Mr Spinney}0 | 0·0009 | 0·13 | 1·25 | 8000 | 65 | Hard graphitic Carbon for small and medium machines. Mica should be recessed. Specially suitable for brushes with a large wearing surface. SN{Mr Sanderson}5 | 0·0009 | 0·14 | 0·75 | 4000 | 65 | Harder than SP{Mr Spinney}0. Suitable for machines with flush Mica, and for brushes with small wearing surface only. SN{Mr Sanderson}4 | 0·0008 | 0·22 | 1·1 | 6000 | 65 | Similar to SN{Mr Sanderson}5, runs well on motor car lighting dynamos with flush mica. Soft-Graphite Brush Grades. Normal pressure 2-3lbs. per sq. inch. SP{Mr Spinney}2 | 0·0005 | 0·14 | 1·1 | 8000 | 65 | A pure graphite brush for stationary machines up to the highest peripheral speed. Silent running. Recessed Mica not absolutely essential. SP{Mr Spinney}1 | 0·00035 | 0·17 | 1·0 | 8000 | 65 | A very soft elastic graphite brush specially recommended for machines with sensitive commutation. Very high polishing quality. Best results obtained with recessed mica. Electrographitised Brush Grades. Normal pressure 3-6 lbs. per sq. inch. SE6 | 0·0009 | 0·21 | 1·2 | 6000 | 65 | Special grade for small AC commutator motors. SE1 | 0·0014 | 0·17 | 1·0 | 5000 | 65 | For DC machines of easy ratings with recessed mica. SE0 | 0·0015 | 0·12 | 1·2 | 6000 | 65 | Electrographitised brush specially for large generators, rotary convertors, etc. Mica should be undercut. SE8 | 0·0013 | 0·19 | 1·45 | 6000 | 65 | Little softer than SE0; specially suitable for machines with very sensitive commutation. Mica should be undercut. SE5 | 0·0022 | 0·14 | 1·4 | 8000 | 65 | For DC traction motors and Battery Vehic'es with recessed mica. SE2N | 0·0016 | 0·18 | 1·2 | 6000 | 65-75 | Specially recommended for AC commutator and variab'e speed motors with recessed mica. High polishing quality. Also used on sliprings where conditions permit. SE9 | 0·00125 | 0·18 | 1·4 | 6000 | 65 | Soft Electrographitised grade. Mica should be recessed. Bronze Brush Grades. Normal pressure 2-4 lbs. per sq. inch. Grade | Spec. Res. Ohms per Inch Cube | Coefft. of Friction | Contact drop at Normal Current Density volt | Approx. Maximum Commutator Speed Ft. per Min. | Normal Current Density, Amps per sq. in. (Commr. / Rings) | Application and Characteristics SB{Mr Bull/Mr Bannister}6 | 0·00013 | 0·11 | 0·8 | 6000 | 60 / 65 | This grade has a low content of copper; recommended for sliprings within the limit of amps stated. SB{Mr Bull/Mr Bannister}5 | 0·000025 | 0·12 | 0·65 | 6000 | 75 / 90 | For very sensitive sliprings with contents of zinc and for plating dynamos up to 30 volt. SB{Mr Bull/Mr Bannister}3 | 0·000013 | 0·13 | 0·55 | 6000 | 80 / 100 | For sliprings and plating dynamos up to 20 volt. SB{Mr Bull/Mr Bannister}2 | 0·000002 | 0·22 | 0·35 | 6000 | 95 / 110 | For copper sliprings and low voltage dynamos up to 12 volt. SB{Mr Bull/Mr Bannister}9 | 0·000004 | 0·085 | 0·3 | 6000 | - / 120 | For copper and forged bronze rings. SB{Mr Bull/Mr Bannister}0 | 0·000005 | 0·25 | 0·25 | 4000 | 130 / 150 | Special bronze brush for low voltage self exciting dynamos. We are always willing to be of assistance to our clients and we cordially invite them to avail themselves of our services. When experiencing difficulties we supply trial sets of brushes; in such cases please fill in the data of the respective machine on our data-sheet which will be sent to you on request. The qualities mentioned in this list are in general use, but besides these grades we have a range of brush qualities for special conditions. Our technical service is always available for troublesome or difficult cases, also for advice and selection of the most suitable grades for given conditions. | ||