Expertly Engineered | Superior Performance | Dependable Reliability

Since 1928, Helwig Carbon has been the American industry leader in the replacement carbon brush market, as well as a supplier to many of the major OEMs of DC industrial equipment. We stock thousands of carbon brushes for a variety of popular applications. Our state-of-the-art manufacturing facility also allows us to quickly produce custom carbon brushes in a day or two.

Our carbon brushes can be custom engineered and manufactured to meet the requirements of your particular motor or generator. Finding the proper carbon brush design for the operating conditions of your motor is the key to maximizing the life of the carbon brush and contact surface. Poor brush selection can result in fast brush wear and damage to the contact surface. Helwig Carbon’s engineers are industry-leading experts on sliding electrical contacts found in:

■DC Motors & Generators
■AC Synchronous Motors
■AC Generators
■Wound Rotor Induction Slip Ring Motors
■Wound Rotor Turbine Generators
■Fractional HP Motors
■Grounding Applications

Let us custom engineer the solution for your application!
Made in USA logo, showing that our bearing protection kits are crafted in the USA, static grounding bearing

Red Top US Patent 3,017,529 Walter O. Helwig
Helwig Carbon Products, Inc. 1962
Absorbs vibration, insulates spring finger, holds sections together for easy installation.
Independent Carbon Sections: Multiflex and Triflex US Patent 2,181,076 William Siebenmorgen
Speer Carbon 1938
Multiple sections increase the resistance between entering and leaving edge of brush which leads to better commutation. The Bias Cut Mutiflex provides better commutation in a stronger design.
Silver Coated Copper Tamping Powder US Patent 2,631,252 Speer Carbon 1953 Tamped connections of wire into carbon with lower resistance and less oxidation. Graphite Tamping Powder US Patent 2,181,076 Speer Carbon 1970 Consistent, low resistance tamped wire connections that function under stressful and varying load conditions. Wear Indicator Est. 1980 Helwig Carbon Wear Indicator Red caution strip provides an easy indicator to see when spring force is declining and brushes should be replaced. Transert Brush Walter O. Helwig Helwig Carbon Products, Inc. 1936 Inserts of different material to optimize life and performance under challenging operating conditions. US Patent 2,105,038 Quick Disconnect Terminal & Mounting System Est. 1962 Very low resistance, high capacity, safe, secure connections that allow for fast, easy brush changes. Constant Force Springs Est. 1983 Helwig Carbon's research and technical report led to recommendations for higher contact force on sliding electrical contacts. The result has been a significant increase in life and performance of carbon brushes.

A carbon brush is a sliding electrical contact that conducts current between the stationary wires of the stator and the rotating wires of the rotor.

Brush sizes are designated as: Thickness x Width x Length of the carbon. If the brush design includes a Red Top, the length measurement should include the pad. On brushes with bevels, the length is measured on the long side. Brushes with a head on top include the length of the head. When specifying dimensions as a reference, submit information on brush length even if it is the worn length.

examples of carbon brushes for brush dimensions

The brush is cut on a slant on the top or bottom and it is the angle other than a right angle on the top or bottom of the brush. Bevels generally range from 0° – 45°

bevels on carbon brushes infographic

The surface of the carbon brush which touches the commutator or slip ring. The condition of the brush face can be a good indicator of brush performance.

The metal top of a brush connected to the block of carbon with a wire or spring. The cap provides the stationary electrical contact. Used primarily in small fractional horsepower motors.

caps on carbon brushes infographic

The curved bottom surface of the brush designed to meet the curvature of the contact surface.
Also referred to as a concave radius.

concaving infographic

The final composition of the raw material. Manufacturers give each unique composition a designation called a brush “grade” See Helwig Grades

Descriptions of the types of brush grades:

Graphite:

  • Graphites are for use in special applications requiring the low friction characteristics of this material. When brushes must operate at very low current densities or very high peripheral speeds, a graphite grade should be used.

Carbon Graphite:

  • Carbon Graphites offer cleaning action for use at slow speeds, low current densities and medium to low voltages. These grades were developed early in the history of motors and generators and are therefore found most often on older equipment, particularly with flush mica commutators.

Electro Graphite:

  • Electrographites are the most common grades used on modern equipment with good performance at high voltages, high current densities and high speeds. There is a wide range of characteristics within this category. Most electrographite grades are capable of handling overloads well.

Silver Graphite:

  • Silver graphites have material contents of 15–95% silver. The added conductivity and lower voltage drop of the metals allow metal graphite brushes to perform well
    at very high current densities and low voltages.

Copper Graphite:

  • Copper graphites have material contents of 15-95% copper or copper alloy. The added conductivity and lower voltage drop of the metals allow metal graphite brushes to perform well at very high current densities and low voltages.

For more information about materials and brush grades, please visit our Grade Information page.

The upper part of the carbon shaped to hold the end of the spring in place. Commonly used on brushes with springs and caps.

Also known as a Helwig Quick Disconnect terminal, is an electrical connection that doesn’t require nut and bolt to hold the terminal in place.

HQD examples for carbon brushes

A series of letters and numbers that delineate a specific brush from another.

How to Properly ID a Carbon Brush

Multi-section brush where two or more wafers come together to form the whole brush. The wires from the various wafers generally meet in one terminal. These brushes are often held together with a Red Top pad.

Combination of hard plastic and rubber square glued to the top of the carbon brush. Pads hold the multiple brush sections together, insulate spring from carrying current and absorb excess vibration. The spring or spring finger will make contact with the brush on the pad surface.

The wire is attached mechanically to the carbon with a rivet. The wire is generally wound around the rivet and up through holes in the carbon material for an extra secure connection.

A wire or wires that connect the brush to the terminal.

shunt length on carbon brushes inforgraphic

Where the wire enters the carbon brush. These locations are numbered in relation to viewing the front of the brush

shunt locations on carbon brushes infographic

Insulation over the shunt wires. Some have a painted cloth appearance and others resemble a soft flexible rubber tubing.

Groove on the top of the brush often used to stabilize the spring. Face slot – cuts in the brush face.

A coiled spring that surrounds the shunt of a brush, connected with a cap. Typically only seen on fractional horsepower brushes.

Coil spring infographic

The wire is embedded directly into the carbon brush.

A device at the end of the wire of a carbon brush that makes a convenient stationary electrical connection.

terminals on carbon brushes infographic
parts of carbon brushes - infographic of the parts of a carbon brush
wireless carbon brush
*Enlarged to show detail

Wireless

  • Sometimes referred to as shuntless motor brushes
  • Commonly used in FHP motors, micro-motors, power tools, household appliances, or other small DC motors
  • Cost-effective parts, manufactured by molding or press-to-size process
  • Style Numbers: P20-P57
example of tamped with spring carbon brushes
*Enlarged to show detail

Tamped with Spring

  • Typically a  smaller brush, with a tamped shunt surrounded by a spring coil and topped with a soldered cap
  • Commonly used in FHP motors, medical imaging equipment, tachometers, aerospace, Bearing Protection Kits™, power/signal/data transmission, and variable transformers (variac brush)
  • Cost-effective parts manufactured by molding or press-to-size process
  • Style Numbers: Q100-Q117
tamped single wire carbon brush
*Enlarged to show detail

Tamped Single Wire

  • A simple design, one wafer, one tamped shunt, one terminal.
  • Commonly used in DC Motors & Generators, industrial, elevators, lift trucks or forklifts, grinders, FHP Motors and paper mills, variable transformers (variac brush)
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: Q20-Q96
tamped multiple wires carbon brushes
*Enlarged to show detail

Tamped Multiple Wires

  • A simple design: one wafer, two tamped shunts, one terminal
  • Commonly used in DC motors, slips-rings, power generation, general industrial, elevator, FHP motor, and railroad
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: Q58-Q99
tamped multi-section carbon brushes
*Enlarged to show detail

Tamped Multi-Section

  • Multi-wafer brushes are typically seen with 2 or 3 wafers and commonly connected to a single terminal. A Helwig Red Top is also popular with multi-section brushes as it helps secure each wafer together, insulate the spring from carrying current, and absorbs excess vibration.
  • Commonly used in elevators, slip-rings, general & heavy industrial, paper mill and railroad
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: 2Q20-3Q25
riveted single wire carbon brush example
*Enlarged to show detail

Riveted Single Wire

  • Typically a single wafer brush, one shunt wire, and one terminal.  Riveted for an extra secure brush-to-shunt connection and often will include a Helwig Red Top or a hammerplate.
  • Commonly used in elevators, slip-rings, FHP motors, general & heavy industrial, paper mills, hydro or other power generation
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: R21-R76
riveted multiple wire carbon brush
*Enlarged to show detail

Riveted Multiple Wire

  • Typically a single wafer brush, with 2 or more shunt wires, and one terminal.  Riveted for an extra secure brush-to-shunt connection and often will include a Helwig Red Top or a hammer plate.
  • Commonly used in elevators, slip-rings, FHP motors, general & heavy industrial, paper mills, hydro or other power generation
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: R41-R56
riveted multi-section carbon brushes
*Enlarged to show detail

Riveted Multi-Section

  • Multi-wafer brushes are typically seen with 2 or 3 wafers and commonly connected to a single terminal. A Helwig Red Top is also popular with multi-section brushes as it helps secure each wafer together, insulate the spring from carrying current, and absorbs excess vibration.
  • Commonly used in elevators, slip-rings, general & heavy industrial, paper mill, and railroad
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: 2R21-2R29
tamped paired motor brush example
*Enlarged to show detail

Tamped Paired

  • Paired brush wafers with separate shunts, commonly connected by one terminal.
  • Commonly used in slip rings, lift truck or forklifts
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: M21-M33
riveted paired carbon brushes
*Enlarged to show detail

Riveted Paired

  • Two separate brush wafers, with separate shunts paired at the terminal. Riveted for an extra secure shunt-to-brush connection.
  • Commonly used in aerospace, lift truck or forklifts, FHP motors or industrial
  • Precision machined by carbon brush experts through state-of-the-art automation and master handiwork
  • Style Numbers: M40-M43

A carbon brush is a sliding electrical contact that conducts current between the stationary wires of the stator and the rotating wires of the rotor.

Helwig’s electrical carbon brushes are made from low friction, conductive carbon materials that include natural graphite, carbon graphite, silver graphite, copper graphite, and electro graphite.

Graphite:

  • Graphites are for use in special applications requiring the low friction characteristics of this material. When brushes must operate at very low current densities or very high peripheral speeds, a graphite grade should be used.

Carbon Graphite:

  • Carbon Graphites offer cleaning action for use at slow speeds, low current densities and medium to low voltages. These grades were developed early in the history of motors and generators and are therefore found most often on older equipment, particularly with flush mica commutators.

Electro Graphite:

  • Electrographites are the most common grades used on modern equipment with good performance at high voltages, high current densities and high speeds. There is a wide range of characteristics within this category. Most electrographite grades are capable of handling overloads well.

Silver Graphite:

  • Silver graphites have material contents of 15–95% silver. The added conductivity and lower voltage drop of the metals allow metal graphite brushes to perform well
    at very high current densities and low voltages.

Copper Graphite:

  • Copper graphites have material contents of 15-95% copper or copper alloy. The added conductivity and lower voltage drop of the metals allows metal graphite brushes to perform well at very high current densities and low voltages.

For more information about materials and brush grades, please visit our Grade Information page.

The proper way to install a carbon brush in a DC electric motor is:

  1. Start by disconnecting the power of the machine with the approved lockout procedures.
  2. Remove the old brushes and inspect (take note of unusual conditions of the brush or brush holders).
  3. Inspect the commutator for any unusual conditions as described in the Helwig Carbon Commutator Condition Guide.  Download here.
  4. Check the inside of the holder cavity for dust, dirt, carbon build-up or burned areas. Clean if necessary.
  5. Check the terminal connections. Clean if necessary.
  6. Now, secure holders to the mount by checking for tightness, proper alignment.
  7. Check the spring force of current springs with a Helwig Digi-Scale and make sure they are within the recommended range.
  8. If the replacement brushes are made from a different grade of material, you will need to remove any old film from the brush tracks. Use a dry untreated canvas or rubber abrasive.
  9. Install new brushes into the holders, paying attention to the orientation of angle holder designs.
  10. Apply the constant force spring. After applying the spring, pull up on the brush and release gently. This makes sure the brush moves freely in the holder.
  11. Connect the terminals, make sure your connections are tight and secure.
  12. Now, seat the brush with commutator garnet paper.
  13. Lastly, for final wear in operate the DC machine at no load.

How to Install a Carbon Brush

Brush sizes are designated as: Thickness x Width x Length of the carbon. If the brush design includes a Red Top, the length measurement should include the pad. On brushes with bevels, the length is measured on the long side. Brushes with a head-on top include the length of the head.

How to Properly ID a Carbon Brush

The much-maligned carbon brush is not responsible for most of the machine malfunctions attributed to it. Sparking at the brush face is usually the first symptom of trouble elsewhere.

Common Reasons for Carbon Brush Sparking:

  • Brush holders are
    • not evenly spaced
    • off electrical neutral
    • damaged or dirty
    • too far from the commutator surface
  • Wrong interpole strength
  • Overloads or Underloads
  • Defective armature windings
  • Incorrect spring pressure
  • Poor undercutting of commutator
  • Foreign material on commutator surface
  • Black commutator film
  • Brushes binding in holder
  • Restricted brush motion
  • Out-of-round commutator
  • High bars or flat spots
  • Machine vibration

For more details and solutions on brush sparking download our FREE version of Brushes, Sparking and Machine Maintenance wrote by M.S. May – Speer Carbon (a Helwig Carbon Products company)

  1. Place commutator garnet paper of sufficient width to contact all brushes with abrasive side out and secure with masking tape the full circumference of the commutator.
  2. Rotate by hand in the direction of rotation until the brushes have taken on 75% of the radius. Eighty grit paper does the primary shaping and should be followed by 220 grit for a fine finish.

To view Helwig’s garnet paper listing click here.                4% discount on orders of 10 or more rolls!

Seating In Carbon Brushes

The numbers on your motor brush display vital information about the brush.

Commonly these numbers include:

  • Grade Information
  • Helwig Carbon Part Number
  • OEM Part Number
  • Customer Part Number

How to Properly ID a Carbon Brush

For specifics to your application, please contact Helwig Engineering to diagnose your brush wear problem.

Call (800) -962-4851 or Contact Us

 

Rapid brush wear is a problem that can be caused by a multitude of factors. There isn’t one easy answer to this question, as each situation can be different. A natural answer to this question that many will quickly jump to is the carbon brush grade. However, we’ve seen that, more often than not, the brush grade is not the culprit.

The NUMBER ONE reason for increased brush wear that we see is from low spring pressure! Inadequate spring pressure can cause rapid electrical brush wear. Clock and fingerstyle springs tend to lose force as the brush wears, and all springs will fatigue over the course of time. This will reduce the effective force at the brush face and increase the rate of brush wear.  Reference our Recommended Spring Pressure Chart for more.

To find out other common reasons for rapid brush wear, read our blog: 3 Reasons for Rapid Brush Wear

As a general rule of thumb, if the carbon brush wears below a usable length, it is time to replace the brush.  Often, signs of cracking, disintegrating, or burning, the brush should be replaced.

When motor brushes wear out, the electric motor will arc & spark, and the electrical circuit may be incomplete. This situation can be dangerous and should be dealt with immediately.  Usually, the problem can be solved by replacing the brushes.

For more details and solutions on brush sparking download our FREE version of Brushes, Sparking and Machine Maintenance wrote by M.S. May – Speer Carbon (a Helwig Carbon Products company)

Carbon brush grades are typically found stamped or marked on the front side of the brush. The grade designates the material composition of the brush.

Brush grades are regularly organized according to the manufacturing processes and the types of materials used. Today’s grades are determined through a variety of raw materials, molding pressures, temperatures, duration of the sintering process and post-process treatments. Material elements provide different levels of resistivity, hardness, and strength that directly affects friction, contact-drop, and surface film.

Lightning Protection Systems

A lightning strike is the result of an electric discharge between the atmosphere and an object. Most cloud to ground strikes are concentrated to a physical location, which is referred to as a “termination”. Interestingly, the bright flash that we call a lightning strike is only about one inch in diameter, even though it seems to be much more significant to the naked eye, video, and photographs.

Fractional Horsepower Brush Design | Fractional HP Brushes | Helwig Blog

Fractional Horsepower Brush Design

Fractional HP (FHP) motors are multi-purpose motors used for a wide range of applications. As space is limited and performance is key, brush-type DC FHP motors offer a significant advantage over

3 Reasons for Rapid Brush Wear

A common question from those handling DC motor maintenance is, “why are my carbon brushes wearing so quickly?”. Rapid brush wear is a problem that can be caused from a multitude of factors. There isn’t one easy answer to this question, as each situation can be different. A natural answer to this question that many will quickly jump to is the carbon brush grade. However, we’ve seen that, more often than not, the brush grade is not the culprit. Here are three of the most common reasons for rapid carbon brush wear: