How to Select Carbon Brushes for Motors and ... - Morgan AM&T

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6 brushes, also known as pads, designed to soften the impact from a rough commutator, giving longer brush life and reducing brush breakage. However, rubber hard top brushes are not a “cure-all” solution. For more information on rubber hard top brushes, refer to the technical data sheet on Rubber Hardtop Brush Applications. Engineered Brush Grades Electrographitic surface. On critical threading conditions, it is recommended that fluted brushes be used, as the brush allows for a quick brush fit and a Spec. more even film. Trans. Res. Strength Con- It Brush is not necessary Ω-in. to Dens. remove the lbf/in² brush after tact the Fric- fluted portion Grade is worn (µΩ-m) away, but g/cm³ can be (kgf/cm²) operated Drop to the normal tion minimum wear length. 0.0020 3700 234 1.48 VH L Pre-Radius Brushes (51) (260) An 0.00075 2700 258 alternate method to form 1.60 the brush to the surface H of L the commutator is (19) to machine a radius (191) (pre-radius) in the brush face. This machining applies a radius that is equal to or slightly 0.0030 1700 561 larger than the commutator. 1.54 Adding VH a pre-radius M does not remove (76) the need to sand (120) in a brush, but it does significantly 0.0029 decreases the time 1600 needed to match the contact 569 surface. (74) 1.53 VH M (113) Rubber 0.0027 571 Hardtop Brushes 1.57 (66) 2400 (169) VH M Morgan 0.0022 3200 581 AM&T manufactures 1.61 a full line of rubber VH hardtop M brushes, also known (56) as pads, designed (225) to soften the impact from 0.0024 3700 590 a rough commutator, 1.62 giving longer brush VH life M and reducing brush (61) breakage. However, (260) rubber hard top brushes 0.0020 4000 591 are not a “cure-all” 1.66 solution. For more VH information M on rubber hard (51) top brushes, refer (282) to the technical data sheet 0.0026 1400 A451 on Rubber Hardtop 1.50 Brush Applications. VH (66) (99) L Engineered Brush Grades Electrographitic Brush Grade 234 258 561 569 571 581 590 591 A451 Spec. Res. Ω-in. (µΩ-m) 0.0020 (51) 0.00075 (19) 0.0030 (76) 0.0029 (74) 0.0027 (66) 0.0022 (56) 0.0024 (61) 0.0020 (51) 0.0026 (66) Dens. g/cm³ 1.48 1.60 1.54 1.53 1.57 1.61 1.62 1.66 1.50 Trans. Strength lbf/in² (kgf/cm²) 3700 (260) 2700 (191) 1700 (120) 1600 (113) 2400 (169) 3200 (225) 3700 (260) 4000 (282) 1400 (99) Con- tact Drop Friction VH L H L VH M VH M VH M VH M VH M VH M VH L SRB does not limit the apparatus output since it is made of the material compatible with the other brushes. SRB’s will remove metal as they slowly grind off the high areas. For more information on SRB’s, refer to the technical data sheet on Surface Rounding Brushes. Surface Cleaning Brushes Surface Normal The surface cleaning brush (SCB) is a preventative Speed Current Description and Application maintenance tool designed to give the best possible ft/min Density performance in rotating equipment exposed to severe (m/sec) A/in² contamination. The SCB fits in the brush holder of the (A/cm²) Recommended for: motor or generator and cleans the commutator and/or 6000 collector 80 ring during A variety operation. of industrial The SCB and FHP does machines. not limit the (30) apparatus (12.5) output. Good For general less purpose aggressive grade. cleaning, please refer to the laminated Copper alloy grades slip listed rings previously. with current For density more 6000 information 80 on SCB’s, up to 75 refer APSI to and the speeds technical up data to 6000 sheet on (30) Surface (12.5) Cleaning ft/min. Brushes. Also used on lightly loaded machines. 8000 Surface 80 Rounding Where Brushes excellent commutating ability is of (41) (12.5) primary importance. Contaminated atmospheres where slight 8000 The surface 80 rounding brush (SRB) is another preventative polishing action is necessary. (41) maintenance (12.5) tool designed to give the best possible performance in rotating equipment (that has a rough riding 7000 surface). 80 The SRB Industrial fits in and the transit brush applications. holder of the motor or (36) generator (12.5) and smooths the commutator and/or collector 6000 ring to a 80 specific Mill-type roundness motors as and the machine generators operates. where The (30) SRB does (12.5) not limit normal the commutation apparatus output is needed. since it is made of 6000 the material 80 compatible Where high with strength the other and brushes. superior SRB’s will (30) remove (12.5) metal as commutating they slowly ability grind is off needed. the high areas. For 6000 more information 80 Where on SRB’s, severe refer mechanical to the technical conditions data sheet (30) on Surface (12.5) Rounding require Brushes. a high strength grade.. 8000 80 Where humidity is low or where filming (41) (12.5) conditions are difficult. Surface Speed ft/min (m/sec) 6000 (30) 6000 (30) 8000 (41) 8000 (41) 7000 (36) 6000 (30) 6000 (30) 6000 (30) 8000 (41) Normal Current Density A/in² (A/cm²) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) Description and Application Recommended for: A variety of industrial and FHP machines. Good general purpose grade. Copper alloy slip rings with current density up to 75 APSI and speeds up to 6000 ft/min. Also used on lightly loaded machines. Where excellent commutating ability is of primary importance. Contaminated atmospheres where slight polishing action is necessary. Industrial and transit applications. Mill-type motors and generators where normal commutation is needed. Where high strength and superior commutating ability is needed. Where severe mechanical conditions require a high strength grade.. Where humidity is low or where filming conditions are difficult. 5 5
Electrographitic Brush Grade AY B344 D DE2 DE25 DE3 DE7 DE7000 DE8 DE869 DE9000 F799 G N19 N38 N39 N44 N48 N6000 Spec. Res. Ω-in. (µΩ-m) 0.0004 (10) 0.0008 (20) 0.0005 (18) 0.0021 (53) 0.0025 (64) 0.0020 (51) 0.0025 (58) 0.0020 (51) 0.0020 (51) 0.0013 (36) 0.0020 (51) 0.0035 (76) 0.0013 (36) 0.0025 (58) 0.0020 (51) 0.00075 (19) 0.0024 (61) 0.0028 (71) 0.0026 (66) (continued) Dens. g/cm³ 1.68 1.65 1.65 1.64 1.69 1.62 1.67 1.67 1.70 1.71 1.68 1.65 1.65 1.61 1.70 1.77 1.50 1.58 1.55 Trans. Strength lbf/in² (kgf/cm²) 3000 (211) 3700 (260) 4200 (296) 3700 (260) 4200 (359) 4500 (317) 4400 (310) 5500 (387) 5000 (352) 4000 (282) 5500 (387) 2800 (197) 3300 (232) 2800 (197) 5000 (352) 4700 (331) 1500 (106) 2000 (141) 2800 (197) Con- tact Drop Friction H M H M H M VH L VH L VH L VH L VH L VH L H M VH L VH M VH M VH L VH L VH L VH L VH L VH L Surface Speed ft/min (m/sec) 4000 (20) 6000 (30) 5000 (25) 8000 (41) 10000 (51) 8000 (41) 10000 (51) 10000 (51) 8000 (41) 6000 (30) 10000 (51) 7000 (36) 6000 (30) 8000 (41) 8000 (41) 10000 (51) 10000 (51) 10000 (51) 8000 (41) Normal Current Density A/in² (A/cm²) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 70 (11) 80 (12.5) 70 (11) 70 (11) 75 (12) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) 80 (12.5) Description and Application Recommended for: Steel or bronze field rings of synchronous motors and wound rotor motor rings up to 100 APSI and up to 4000 ft/min. Low voltage battery lift trucks where low contact drop is required. Steel and cast iron slip rings. Smaller diesel-electric locomotive main generators and auxiliary equipment motors and generators. Traction and hoist motors operating under severe conditions of temperature and low humidity. Transit traction motors. Traction motors and wheel motors in off highway vehicles where high loads and low humidity are present. Also suitable for motors in transit applications. Diesel-electric traction motors providing good commutation and long life. Larger diesel-electric locomotive main generators, and other auxiliary equipment motors and exciters. Brass collector rings, also used for medium commutating service. High speed locomotive traction motor applications. Applications where friction chatter is encountered. Medium-duty commutating service. Medium to low current density applications with normal commutation requirements. Industrial generators and exciters where long life is necessary . Exceptional ability to maintain film under lightly loaded conditions. Slip rings where a stabilized film is critical and long life is necessary. High commutating applications from large heavy duty motors and generators to less critical applications. Where excellent commutation is required and sustained high loads are present. Low or variable humidity conditions and where long periods of light loading are a factor. Slight polishing action, also controls film in heavily loaded applications. 6 7
Page 1 and 2: 1 How to Select Carbon Brushes for
Page 3 and 4: Grade Characteristic Definitions Gr
Page 5: St = 3 x P x L / ( 2 x W x T²) St
Page 9 and 10: Electrographitic (continued) Brush
Page 11 and 12: 1 2 3 251 Forrester Dr. Greenville,
Page 13 and 14: T508 T550 T563 T566 T573 T583 T606
Page 15 and 16: ush design or electrical adjustment

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