Frequently Asked Questions


Q: What is the maximum pressure I can run your products at?

A: Generally 80 psi is maximum recommended pressure. Although some spring engaged units may require as much as 100 psi to fully disengage.


Q: What is the maximum speed of Air Champ products?

A: The recommended maximum speeds for Nexen products are listed in the performance tables in the catalog. Maximum speeds are determined from the bearing manufacturer's speed limits and the safe operating speed of the spinning part's material. Air Champ product parts are typically constructed of steel, Class 40 iron and Ductile iron. Each type of material has a safe operation speed, expressed as peripheral velocity limits, and is based on the tensile strength of the material.


Q: What is the maximum temperature limit of Air Champ products?

A: The case temperature of Air Champ Clutches, Brakes and Torque Limiters, measured on the air chamber, is limited to 180° F (85° C). Temperatures above 180° F indicate that the thermal capacity of the unit has been exceeded. Hot - to- the- touch is usually on 140-150° F (60-66° C) Thermal capacities are limited to the maximum allowable temperatures of the o-ring seals, friction material and the bearing lubricant. The thermal capacities are determined by operating a unit at maximum speed and torque levels in controlled circumstances in a test laboratory.

The temperature limits of the components used in Air Champ products is as follows:

• Friction Material 400° F (200° C)

• O-ring Seals - Buna N material 250° F (121° C) Viton material 400° F (200° C)

• Bearing lubricant - Chevron SRI 347° F (174° C)


Q: What type of air controls are used to operate Nexen's clutches and brakes?

A: Air Champ products use a very small amount of compressed air to engage or disengage. 92% of Air Champ products have air chamber volumes from 1-10 cubic inches and do not need a control valve larger than a Cv of 1.0. Nexen has selected 3, 4 and 5-way valves within this range and have them packaged in control kits for customer convenience. For units with air chamber volumes larger than 10 cubic inches, a larger capacity valve may be required.

Quick Exhaust Valves greatly enhance clutch-brake performance. With quick exhaust valves installed, the air chamber pressure exhausts right at the air inlet instead of traveling back through the control valve. A Quick Exhaust valve decreases exhaust times eliminates overlap in Modular clutch-brakes. Use Quick Exhaust valves whenever long airlines are used to increase response times.

Adjustable flow control valves are used to slow the flow in air engaged clutches or brakes when soft starts or ss are required.


Q: Is airline lubrication required for Air Champ clutches and brakes?

A: Nexen recommends the use of lubricated air to extend the life of the O-ring seals. If airline lubrication is not practical, the air supply should be filtered to five microns or better, and maintain a dew point of 40° F or lower.

Note: Many valves require lubricated air. If using non-lubricated air, select a control valve that can operate without lubrication. If a lubricator is used it should be located above and within ten feet of the unit.


Q: What lubrication is required for Air Champ products?

A: Use a low-viscosity oil such as SAE-10 weight oil.


Q: How can I tell what linings I have in my unit and what's the difference?

A: Nexen applies a paint marking to the outer edge of our facings and are as follows:

Purple = High Coefficient, provides 40% more torque capacity than standard linings. Typically used to extend a products range to eliminate the need to go to a larger unit.

Red or Yellow = Standard Coefficient, as shown in torque charts in catalog.

Green = Low Coefficient, provides 60% of the standard torque capacity. Typically, used for soft starts or constant slip applications i.e. tension control

(Caution - carefully calculate thermal horse power requirements).

Blueish in overall color (no paint mark) = Teflon, provides 40% of the standard torque capacity. Typically, used for constant slip applications ie: tension control.

The various nonstandard linings are available in all units. Contact a Nexen representative to determine what is available. To generate a new torque curve based on a nonstandard lining multiply the units torque rating at 80 psi by the appropriate factor (i.e. 1.4 for High Coefficient), locate the new point on the 80 psi axis and draw a straight line to the origin of the existing line.


Q: I don't see exactly what I'm looking for in the catalog, does Nexen have products not listed in the catalog, or can Nexen make me what I need?

A: Nexen does have products that do not show up in the catalog. Contact us for more information


Q: How do I keep the air chamber from rotating on the Air Champ Clutches? Do I need a torque arm?

A: Air Champ clutch air chambers are bearing-supported and use the supplied air hose to prevent rotation. When the clutch engages, the hose will be tugged slightly - this is normal.

Since the air chamber moves back and forth when actuating Nexen advises against the use of rigid airlines or torque arms. Using rigid torque arm or airline would interfere with the air chamber movement and lead to failure.


Q: How does speed reduction in my drive train affect my clutch/brake needs?

A: The torque requirement for a clutch or brake is affected by the speed of the clutch or brake within a power train. Generally, the faster the shaft, the lower the torque requirement becomes. Mechanical speed reduction has a direct multiplying effect on the torque. Example: If a motor drives a 50:1 gear reducer, 100 of motor torque would result in about 5,000 torque at the reducer output shaft. However, the amount of kinetic energy (heat), that the clutch or brake must deal with remains the same.


Q: What is needed to repair a clutch or brake?

A: Instruction Manuals are included with each product and contain the procedure for disassembly, repair and re-assembly.

The items needed to repair a Nexen product are:

  • Tools: screwdriver, retaining ring pliers, a small bench press and assorted wrenches
  • Anaerobic locking compounds: Loctite 242 thread locking compound, Loctite 680 for bearing mounting and safety solvent to clean the surfaces prior to Loctite application
  • Lubricants: "Never-Seez" spline lubricant and "Lubriplate" portable tool grease for o-ring seals.

Q: Can Nexen rebuild my product?

A: Yes, Nexen has a repair department for repairing and rebuilding products. Just contact your local Authorized Nexen Distributor for details.


Q: How does this product work?

A: This product uses spring energy to clamp onto the profiled rail. It is generally used in situations where customers require precision holding or want a redundant braking device. It is released by using air pressure to overcome the spring force. The brake can also be used in E-stop situations in case of a power failure.


Q: Can the brake do repeated dynamic stopping?

A: No, the primary use of the brake should be holding or limited E-stops. Depending on the application there can be a large amount of energy transferred during an E-stop expediting product wear. Contact Nexen for details about your application.


Q: How straight does my rail need to be?

A: The new generation of rail brakes allows more freedom than the competition, with three times more clearance. Although this allows for more flexibility in mounting, it is still critical that the rail be straight. As Nexen's installation and maintenance manual states, we do recommend the rail be mounted up against a machined reference edge.


Q: What if I need more holding force?

A. Multiple brakes can be used on the same rail to multiply the holding force of the system.


Q: What is the expected life of the brake?

A: Each size brake has been fully tested to hold the rated holding force over 1 million holding cycles. If your application calls for an E-stop it will affect life relative to the amount of energy required to do the stop.


Q: Do I need to adjust my brake when I get it?

A: No, the brake is factory set and tested on the rail it was ordered for. You should not need to adjust the brake unless you replace the facings.


Q: Is the product IP rated?

A: As there are multiple vent holes that are open to the air it is not recommend the brake be used in an IP environment.


Q: Are there any special rail requirements?

A: No, standard rail will function properly.


Q: Is installation difficult?

A: Installation is made easier by simply placing the rail brake on the rail, engage it so it self centers and tighten the bolts.


Q: Can Nexen make brakes for rail not found in the catalog?

A: Yes, just provide us with the rail type and dimensions and a brake can be custom made for your application.


Q: How does this product work?

A: The rod lock is a high precision device that uses spring energy to clamp on a round guide rail or a piston shaft. It is used in holding and emergency stop applications. The clamping mechanism has a large surface area to ensure the rod is not damaged upon engagement. The rod lock uses air pressure to release the clamp allowing the system to move freely.


Q: What is the maximum holding force of a rod lock?

A: The maximum holding force available in Nexen's 8" rod locks is 5026 lbs.


Q: Does the rod lock have any holding torque in the case of a rotating shaft?

A: No, this lock is made exclusively for linear holding. Rotating the shaft while the lock is engaged can damage internal parts. Nexen has a large variety of rotary products to fit every need for rotary motion control.


Q: Can standard rod locks be used in wash down?

A: Wash down is such a broad term it is difficult to say for sure. Our lock is anodized and IP67 (inclusion protection) rated. We can also do customized rod locks to fit your needs.


Q: What kind of shafting can I use, and with what tolerance?

A: Shafting must be hardened to a minimum of 52 HRC. The shaft tolerance changes per size ranging from (+.000"/-.0015") to (+.000"/.003"). Refer to the drawing of your lock for exact values.


Q: Can the brake do dynamic stopping?

A: No, the primary use of the brake should be holding or limited E-stops. Depending on the application there can be a large amount of energy transferred during an E-stop expediting product wear. Contact Nexen for details about your application.


Q: How does the manual release feature work?

A: The manual release feature is a provision added to the lock to allow a customer to release the lock without the use of air pressure. This can be helpful in assembly and power outage situations.


Q: Can the lock be used as a guide?

A: Although the lock does come with 1 or 2 linear bearings (depending on the model) it is not recommended that the lock be used as a guide.


Q: Can the shaft leave/re-enter the lock during use?

A: No, the system is guided with linear bushings that have a precision fit. The system may jamb if the shaft is forced into the lock without proper alignment.


Q: Can the brake be used to hold/release stored energy?

A: No, releasing stored energy is basically the opposite of a dynamic stop. Dynamic stops will wear the collar and shaft reducing the product life.


Q: How does this system work?

A: The Roller Pinion System (RPS) is an innovative approach to linear motion. Although it's visually similar to involute gearing, it functions much differently. The key is the roller pinion. Instead of formed metal teeth, the pinion is comprised of rolling pins; each supported by two needle roller bearings. This allows for friction-free motion as the rollers engage a patented tooth profile that is engineered to perfectly match the path of pinion. The friction free meshing also allows the pinion to be preloaded into the rack, eliminating all mechanical clearance.


Q: How smooth is it? It looks like speed would vary as it rolls?

A: Actually, the RPS is exceptionally smooth, rivaling the best classes of ball screws and linear motors. This is achieved with the engineered profile, causing the roller to spin at all times.


Q: What is the pressure angle, and how does it compare to regular rack and pinion?

A: The average is approximately 23 degrees. Unique to the RPS, the pressure angle changes as the roller runs across the working surface. Note, however, that there exists a balancing effect as additional rollers come into contact. The load is shared, and thus, the variance in pressure angle is mitigated. Comparatively, conventional rack in our class is typically around 20 degrees. This means the separation forces, on average, are similar with the RPS to conventional gearing.


Q: Why would I use this instead of precision ball screws?

A: Higher speeds, unlimited length, and lube-free precision. The RPS is unrivaled in its combination of features. It is exceptionally precise and smooth, and with its unique design does away with the limitations of conventional systems.


Q: Why would I use this instead of precision rack and pinion?

A: Zero-backlash, ultra-high efficiency, and quiet, fluid motion. Due to its engineered tooth profile and its rolling action, the RPS is unrivaled its combination of features. It is exceptionally precise, and with its unique design does away with the limitations of conventional gearing.


Q: Under what conditions can this system run lube free?

A: At moderate speeds, at or below 0.5 m/s (1.6 ft/s), the Raydent coated, premium rack is suitable for lube-free running (consult your Nexen representative for further details). The Raydent treatment provides an ultra-hard surface with a dry lubricant. When combined with the rolling action of the pinion, no grease is required.


Q: Do you make stainless steel RPS, or do you have any special coatings for demanding environments?

A: Yes, we have both. However, we do not recommend making the RPS from stainless steel, as we prefer to use special coatings. Reason: The RPS rack needs to be hardened, and this requires the use of martensitic series stainless. Unfortunately, martensitic stainless are not very corrosion resistant. Instead, we recommend using a number of special Raydent coatings that not only protect the RPS from the elements, but also augment performance.


Q: Is installation difficult?

A: "It's simpler than the other rack and pinion we use". Several Nexen customers when installing the RPS for the first time have echoed this statement. The RPS is a precision system, the better the supporting elements, the better the performance. The key is ensuring all the components (bearings, supports, alignments) and installation practice correspond to the level of precision desired.


Q: What is Raydent?

A: The Raydent coating is comprised of a hard chrome base with a polymer infusion. The process creates a hard, durable coating that is permanently bonded to the substrate. There are several options of Raydent available that can handle a variety of demanding applications.


Q: How critical is the preload?

A: To achieve zero-backlash and the accuracy Nexen publishes, it is important to keep the system preloaded. This will ensure two opposing rollers in contact at all times. To simplify machine integration, Nexen offers a factory designed preloader system for use with ISO 9409 gearboxes.


Q: How does this system work?

A: The Roller gear system is an innovative approach to rotary motion. Although it's visually similar to a typical involute gear, it actually functions much differently. The key is the roller pinion: instead of teeth this pinion is comprised of full rolling elements. Each roller is supported by two needle roller bearings making them free of any type of sliding friction. Then, the roller pinion is combined with a gear containing a patented profile that creates a perfectly smooth motion. The major benefit of the rolling action is that the pinion can be preloaded into the gear eliminating all mechanical clearance, making it virtually backlash free and 99% efficient.


Q: What sizes can I get?

A: Due to Nexen's ability to make gears in segments there is no limit to the size of the gear that can be made. That also allows customers to purchase only the amount of an arc needed instead of a full gear. Even compound gear curves can be produced.


Q: What is the torque circle diameter as described in Nexen Literature?

A: This system does not have a "pitch circle" as commonly known in the gear industry. Therefore Nexen provides a theoretical torque circle diameter to be used by system integrators to calculate aspect of their systems such as bearing load. This torque circle diameter correlates to the perfect rolling diameter between the pinion and gear.


Q: Can I select different pitches with the same gear/pinion?

A: The pitch of the roller pinion cannot be changed; therefore Nexen offers 6 pinion sizes to be sure we have something to fit your needs. If one size does not offer the right gear ratio or torque for your system Nexen can generally go up or down a pinion size to meet your needs.


Q: Are gears segmented, and if so when?

A: Gears are segmented when they are larger than approximately a 1m diameter. If the gear is segmented Nexen requires the use of an alignment tool to properly assemble the gear. See "How does the alignment tool work?".


Q: How does the alignment tool work?

A: The alignment tool is composed of 4 pins used to locate one segment relative to another. If your system requires a full gear, an alignment tool must be used at every joint. This will ensure the last gear aligns properly with the first gear. Nexen installation and maintenace manuals provide step-by-step directions if you need more information.


Q: Is installation difficult?

A: The roller pinion system is a precision component so proper installation is important, but not difficult. The key is ensuring all the components building up to the gear are to the same level of precision you want the final system to have.


Q: Why would I use this instead of a standard gear?

A: Efficiency, precision, design flexibility, backlash free operation and low noise are just a few examples of why a Roller Gear System would work well for you.


Q: How can the efficiency be 99%?

A: It's all due to the patented full rolling technology, no sliding friction means high efficiency!


Q: How does this product work?

A: This product is a spring applied, true zero backlash brake based on Nexen's patented wedge facing technology. The servo brake uses pressurized air to release the clamp allowing the system to move freely.


Q: If I over torque the brake will it damage the brake?

A: No, the brake will slip internally, but the motor shaft is directly coupled to the output. That means that if the brake is over-torqued by the output it will spin the motor shaft.


Q: Is it really zero backlash?

A: Yes, our patented wedge interface provides a true mechanical lock between the hub and ground.


Q: Can custom input/outputs be made?

A: Yes, Contact us.


Q: How much overhung load can this product take?

A: This varies by size. See the Nexen tech data sheet for more information.


Q: Can servo brakes be stacked for more torque?

A: Yes, all the inputs/outputs are configured so they can be stacked as long as they dimensionally match up. Just ensure that the components can handle the torque.


Q: Can the servo brake be used in all orientations?

A: Yes. It will function properly in every orientation.


Q: What is IP67 and what does it mean?

A: IP67 classification refers to enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, against hose-directed water and the entry of water during prolonged submersion at a limited depth; and that will be undamaged by the external formation of ice on the enclosure.

6 = Totally protected from dust.

7 = Protected against the effects of temporary immersion between 15 cm (16-inches) and 1 m (40-inches).


Q: Are there other valve options available?

A: Customers may opt to use their own preferred valve, however, Nexen has only tested the Dynamco valve with the Eclipse line of brakes. Nexen cannot assure that other valve options will cause the brake to react the same way it does with the Dynamco valve.


Q: How quickly does the brake engage and disengage?


Size Set (on Time, ms) Release time, ms
2 8 92
3 12 75
4 50 80
5 60 100


Q: Are servo motor brakes available to fit NEMA 23, 34 & 42 frame motors?


 NEMA Frame, Dim. A Nexen Model Bore/Shaft Dia, Dim B Shaft Length, Dim. C Pilot Dim. D Pilot Depth, Dim. E Bolt Circle, Dim. F Product Number
23 (2.25") SBP-2 .250/.250 1.250 1.500 0.095 2.625 964606
23 (2.25") SBP-2 .312/.312 1.250 1.500 0.095 2.625 964611
23 (2.25") SBP-2 .375/.375 1.250 1.500 0.095 2.875 964605
34 (3.62") SBP-3 .500/.500 1.250 1.500 0.120 2.875 964722
34 (3.62") SBP-3 .625/.625 1.180 80/2.875 .200/.120 90-98 964716
42 (4.92") SBP-4 .625/.625 1.500 2.187 0.120 4.950 964833
42 (4.92") SBP-4 .625/.625 2.000 2.500 0.120 4.950 964834
42 (4.92") SBP-4 .625/.625 2.063 2.188/4.500 0.180 5.875 964835


Q: Can an Open Loop (TCD 600) Tension Controller be used on wire or single strand textile materials?

A: Yes, but only with the Proximity Switch and Optical Encoder sensor package. The Ultra Sonic sensor has a hard time sensing the surface of either material type. And the Proximity Switch only sensor package will over correct by reducing the air pressure too fast because it assumes each revolution reduces the radius by the thickness of the material. This is not correct for a spool of material that reduces radius only once for each layer of material, not each revolution of the spool as with flat material like paper or woven textiles.


Q: Is it possible to use other manufacturer's sensors with Nexen Tension Controllers or read out devices?

A: It is possible to use several common brands of strain gage type tension sensors with the TC 820 Tension Controller and some of Nexen's other tension sensor based products. It is always best to check compatibility with a Nexen technical representative for this type of application.


Q: Is an FRL (filter, regulator, lubricator) set needed with Nexen I to P (amperage to pressure) Converters?

A: No, the standard FRL set is not needed or recommended. The I to P Converter is, by definition, a pressure regulator. Due to the small internal orifices in I to P Converters a lubricator should never be used. The proper filtration package is a 5 micron, Auto Drain Pre-Filter (Nexen Product Number 912005), and a 0.01 micron Auto Drain Final Filter (Nexen Product Number 912006). This package provides extremely clean air, which will not clog the small internal orifices of the unit. If the system air provided to the I to P Converter is at a pressure in excess of 100 psi an Air Pressure Regulator (Nexen Product Number 940001) should be provided to reduce the pressure to about 85 psi.


Q: Is it possible to delete one or more calipers on a multi-caliper brake during the unwinding of a single roll of product?

A: Yes, it is possible to do this. It should be done only when using a closed loop control that can compensate for the disappearance of a major percentage of the brake's torque range. It is also best to use a flow control valve when doing this to slowly drop the caliper out of the system, making it easier for the controller to maintain a smooth transition without tension upsets.


Q: Will low coefficient of friction brake pads or facings wear out more quickly then standard coefficient of friction pads or facings?

A: No, in fact they will wear more slowly for any given amount of work accomplished. The work done by a brake or clutch is expressed in Horsepower-Hours, or kW hours. The rate of wear of the friction elements is expressed in Horsepower Hours per cubic inch, or kW Hours per cubic centimeter of facing material. In all cases the wear rate for the low coefficient of friction materials is lower than for the standard coefficient materials.