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Frequently Asked Questions

Trifecta Questions

What is Trifecta?
Trifecta is a pre-adjusted hub assembly - STEMCO's latest commercial vehicle wheel end innovation launched in 2018. The assembly combines STEMCO's high performance Discover XR seal, the revolutionary Zip-Torq axle fastener, precision bearings, a spacer optimized for lubricant flow, and the Defender ESP hubcap, all housed in a precision machined hub. The combination of these premier components ensures mistake proof installation and less downtime; providing fleets the Trifecta of SAFETY, PERFORMANCE, AND CONFIDENCE.
What does pre-adjusted mean?
Pre-adjusted hubs eliminate the need for bearing adjustment. The precision manufactured bearings, spacer, and hub provide a fixed dimensional distance between the inner and outer bearings eliminating the need to manually adjust the bearings. A torque wrench must be used to set the axle fastener according to the pre-adjusted hub manufacturers recommended torque setting, with no backing off the nut. 
What tools do I need to install the Trifecta hub?
The only tools needed are a torque wrench and socket. See the following table for socket sizes required for Zip-Torq and Trifecta. 
Where can I buy service hub assemblies or components?
Trifecta hub assemblies and components can be ordered through the independent aftermarket or original equipment dealers. For more information, contact your STEMCO distributor, local STEMCO sales person, or call 1-800-527-8492. In Canada, call 1-877-232-9111. 
What are the service intervals?
The recommended service intervals are detailed in STEMCO's Tech Tip #21 and TMC's RP 631. 
Which lubricants are approved with the Trifecta pre-adjusted hub?
The list of approved lubricants can be found in STEMCO's Tech Tip #34.
Why does the spacer have holes?
The STEMCO patent pending spacer is designed with six center holes allowing lubricant to reach the mating surfaces between the interior diameter of the bearings and the spindle. The improved lubricant flow prevents fretting and associated corrosion from lubricant contamination, increasing bearing, seal and spindle life. Traditional spacers are solid and tend to block lubricant flow to the mating surfaces, potentially leading to fretting corrosion and frozen hubs.
Can I remove the spacer?
Yes, the spacer can be removed. If the spacer is removed, the bearings must be adjusted manually following TMC RP 618 procedures. Please refer to STEMCO's Tech Tip #50 for more information. 
What are half stand bearings?
Half stand bearings are precision bearings manufactured to a tighter tolerance than standard bearings. They are used in pre-adjusted hub assemblies to eliminate the need for manual bearing adjustment. STEMCO's half stand bearings can be identified with the prefix HS. Bearing cups and cones are a matched set and must be replaced as a set. Only STEMCO half stand bearings are approved for the Trifecta pre-adjusted hub assembly. 
What is GlideLock?
GlideLock is a patent pending feature on the ID (interior diameter) of the Discover XR (Extreme Runtime) seal. GlideLock significantly reduces the installation load on the seal, which helps maintain the integrity of the sealing lips during hub mounting and reduces the potential for heat generation and cocked seals. 
Does the Discover XR seal require pre-lubrication?
The Discover XR seal’s GlideLock technology is designed to perform with or without pre-lubrication, eliminating one of the industry’s leading causes of seal failure—heat.
Will the STEMCO components work in a non-Trifecta hub?
The Discover XR seal and the Zip-Torq axle fastener can be used in any commercially available wheel end. The STEMCO spacer is designed to work only in a Trifecta pre-adjusted hub assembly.
Can I use Pro-Torq or Zip-Torq axle fasteners with other pre-adjusted hubs?
Yes. Pro-Torq and Zip-Torq can be installed with other brands of pre-adjusted hubs. However, Pro-Torq can be used with the system, replacing Zip-Torq during routine maintenance.
Are STEMCO hub caps required with the Trifecta hub?
Yes. To ensure lubricant integrity and proper venting in long life wheel end systems, and to maintain the STEMCO warranty, the Trifecta hub requires STEMCO Defender or aluminum hub caps with STEMCO's ESP or Sentinel technology. 
Can I convert the Trifecta hub to a manually adjusted hub?
Yes, the spacer can be removed and the bearings can be adjusted manually following TMC 618 procedures. Please refer to STEMCO's Tech Tip #50 for more information. 
What are the axle fastener torque specs for the Trifecta hub assembly?
The Zip-Torq axle fastener torque specifications in a Trifecta hub are 200 lb/ft for the steer and drive axles. Simply torque the nut to 200 lb / ft and spin the hub one full rotation. Repeat two additional times.  Do not back off the nut.
What are the currently available applications?
The part numbers currently released include the following TRUCK applications: 5.44" offset FF (steer axle) and Long-Barrel R (drive-axle). The FF applications are a common Freightliner application. The long Barrel R is also a typical Freightliner application, as well as some PACCAR drive axle applications. 
Where can I get more information?
Please visit or call 1-800-527-8492 for more information. In Canada, call 1-877-232-9111.

Intelligent Transportation System Questions

Are your sensors compatible with other RFID systems or Readers?
Our sensors communicate to the BAT RF System using a novel protocol and therefore can not be read by other systems. Sensor data can, however be integrated with many popular tracking systems via our mobile on-board reader.

Are sensor batteries replaceable?
No… we factory seal each unit to insure long operation and protection from the environment. Battery life is sufficiently designed for a long, maintenance free life.

What is the battery life of the sensors?
7 years is the expected nominal life for BAT RF sensors (AirBAT & TracBAT).

What is the operational temperature range of the sensors?
All BAT RF sensors are designed to operate between -40F and 158F.

What frequencies do BAT RF sensors use?
All BAT RF sensors operate within the 2.4GHz industrial scientific and medical(ISM) band. They use a spread spectrum protocol which enhances their immunity from interference.

Are your sensors approved for use in any other countries?
Our solutions are currently approved for use in the U.S., Canada and Mexico.

Are there other sensors in your plan?
Yes, our plan is to add many more sensors that will work with the same architecture.

How may miles of testing have been done?
Millions of miles over the last 10 Years.


AirBAT Questions

What is the warranty on the AirBAT sensor?
AirBAT has a 1 year warranty.

Does the AirBAT cold compensate?
No, we provide an accurate measurement of the actual tire pressure. Cold compensation causes confusion for maintenance personnel. When adjusting cold tires, pressure readings should be actual. Industry mechanics check tires cold to prevent under inflation. 

What is the operating pressure range of AirBAT?
20psi to 150psi.

Are there any temperature range issues with the AirBAT?
No, AirBAT maintains a +/- 3 PSI accuracy across the full operating pressure range.

How long does it take to install AirBAT?
About 5 minutes per wheel end.

Does AirBAT require the tire to be dismounted or removed?
No, AirBAT is externally mounted to the wheel hub cap or lug nuts with a simple bracket. Installation is quick and easy.

Are the hoses on AirBAT serviceable in the field?
Yes, The 2012 release of AirBAT now features thumb nuts on the sensor end of the hose that can be easily connected to the AirBAT sensor and are field replaceable.

Does the AirBAT affect tire balance?
The AirBAT mass is sufficiently low as to not affect balance when mounted near the center of rotation with the recommended bracket.

Do you offer AirBAT for steer tires or wide-based singles?
Yes. Our AirBat SST is designed for steer tire applications and our Single tire AirBat works on wide based singles

Can AirBAT alert me of a tire problem while on the road?
The driver is alerted by the AirBat Driver Alert System (DAS) in cab; additionally we offer over the road email alerts sent to the office through our partnership with SkyBitz for remote trailer applications via the BatRF Asset Interface Module (AIM). For tractor applications, email or SMS text alerts are available through our partnership with PeopleNET via the BatRF Tractor Interface Module (TIM).

Can AirBAT equalize duals or inflate tires?
No, although products like these can offer benefits, we believe the simplest solution is the best.

Will AirBAT comply to future regulations of in-cab warnings?
Although no specific legislation has been handed down, we are closely monitoring government activity in this area. It is our intention that AirBAT will enable fleets and OEM´s to quickly comply with any rulings passed by government.


VESPER Questions

What is Vesper used for?
Vesper is a software program that receives data from a HandBat unit and places that information into a CVS file for manipulation or upload into other software programs. 
What hardware does Vesper connect to?
Vesper connects with all AirBat units via HandBat
Is there a way for each TracBat be linked to a specific truck number so when scanned, the user will know which truck it is?
Yes, the customer can enter the truck number into the Notes Field after a download on a given TracBat. All future downloads after that point will tie that TracBat to that entered number. 
Does Vesper connect to WebBat?
Do I need more than one Vesper POD if I have more than one location and HandBat readers?
Can I transfer the data from Vesper to my other software systems?
Data is saved in a CSV (comma separated variable text format). Any system that can take in a .csv file can import this data. 
How many readings can Vesper take?
400 readings can be stored in a HandBat unit and then downloaded to the Vesper Pod. 
Can I track battery life of my sensors through Vesper?
All parameters that are in the sensors can be seen in Vesper. 
If I have multiple locations and readers how can each handheld unit collate all the remote readings. For example - each site has a laptop, HandBat / download POD and Vesper software - can all readings be collated in a web based system?
This would be up to the customer to create that system. 
Can Vesper link all the readings from each site together (what is the easiest way)?
This would be up to the customer to create that system. 
Does Vesper work with all HandBat Readers (Which Older Versions are Compatible)?
Any 018200002 or 018200000 HandBat will work with Vesper with any software version. 
Will Vesper work on my iPad or Tablet?
No, Vesper only works on Windows 7 or later. 

TrailerTail® Questions

How much will I save? 
Typical results are 3 cents for every mile you drive, or an average of 8 gallons of fuel for every 1,000 miles of operation.

How is the TrailerTail® tested?
TrailerTail® performance has been proven in dozens of tests, including computational fluid dynamic modeling, wind tunnels, test tracks, and on-road fuel efficiency measurements. The minimum fuel efficiency improvement was .3 miles per gallon and the maximum efficiency improvement was .6 miles per gallon, with the average fuel efficiency benefit of .4 miles per gallon across all tests.

How durable is TrailerTail® equipment?
Trucker-Tough Panels: Reinforced thermoplastic panels give with impact and bend back to their original form.
Temperature Resistance: Highly inert materials maintain their shape in extreme heat and cold.
Weather Resistance: Panels do not bond with snow and ice allowing for peak aerodynamic performance even through storms. 
Galvanized Steel Hardware: All-weather performance tested over billions of miles
Patented Swing-Arm System: Allows panels to maintain rigidity when deployed and collapse completely when closed.

How much maintenance does a TrailerTail® require?
Virtually no maintenance.

Part                Time to Repair Chart
Gas Springs       5 Minutes
Cables 5 Minutes
Latches 6 Minutes
Minor Collision   15 Minutes
Major Collision   30 Minutes


  • A representative sample population of 1,000 trailer tails traveling 55 million miles over 12 months resulted in 4 minor (<15 minute) repairs and 1 driver-caused collision (<30 minute) repair.
  • STEMCO components have undergone over 2.5 billion miles of on-road experience and refinement.
  • Nationwide service statistics indicate less than 1% of all trailer tails were involved in rear-impact collisions.
  • Average collision repair time: 16 minutes

How do I ensure TrailerTail® deployment?
Fleets can guarantee near 100% deployment of their TrailerTail® equipment with basic driver training and the use of driver notification decals provided for the front of the trailer and landing gear. Alternatively, the electronic speed-sensing AutoDeployTM system is available as an option for fleets wishing to guarantee fuel savings at 35 mph and above regardless of driver participation.

How does TrailerTail® Technology perform in winter?
Weather Resistance: Panels do not bond with snow and ice
Temperature Resistance: Highly inert materials maintain their shape in extreme heat and cold
Galvanized Steel Hardware: All-weather performance tested over billions of miles

If snow is still a concern for you, we recommend Trailer Tail® Trident: a 3-sided device with no bottom panels eliminating any possible accumulation of snow in the TrailerTail cavity.

How do I know it really saves fuel?
TrailerTail® fuel savings has been verified by each of the over 500 fleets that have purchased and pulled TrailerTails® over 4 billion miles. Extensive third-party (SAE Type II J1321) on-road testing as well as wind tunnel testing has proven that STEMCO TrailerTail® technology can save 5-7% at highway speeds. 
Do I need TrailerTail® if I have skirts?
Yes. Skirt adoption by most modern fleets is peaking as operators have invested to survive economically and comply with regulatory change. Adding TrailerTails® to skirt-equipped trailers adds an additional 5% in savings. The largest remaining opportunity for fuel savings on a tractor-trailer today is with TrailerTail®.
I have a 3:1 ratio of trailers to trucks; will my return on investment take too long?
For a tractor driving 120,000 miles per year, divided by 3, is 40,000 miles per year. At $3/gallon, the fuel savings is over $1,000 per year, with an ROI of less than 2 years. 

TracBAT Questions

What is the warranty on the TracBAT sensor?
TracBAT has a 1 year warranty.

What is the accuracy of TracBAT?
+/- 2% over the life of the unit.

What are the limitations of TracBAT?
Excessive speeds (above 120mph for typical 22.5″ rims) are not accurately supported. The LCD can cease to display in extreme cold (less than -40F). However, the unit can still be read by all BAT RF Readers in these conditions.

Does TracBat continue to count up when in Reverse?
Yes, the unit also works on either side of the vehicle.
How far can I go and still reprogram my TracBat settings?
TracBat unit's settings will be permanently programmed after 2 miles of use. 


WebBat RF® Questions

What are the fees for the WebBAT?
Contact a representative for the current pricing model.

How often will WebBAT require upgrading?
Because WebBAT is an Internet application, any and all upgrades will be made available to all customers as they are released without need for local upgrades or installation. New features will be added to WebBAT as the system is expanded.

What is the best method to verify all vehicles have tags assigned?
Run the All Tags Under Management report with sort criteria set to Order List by Unit Id. 

Is STEMCO's TPMS info shown in cab on the OBC Tire Monitoring Graphic screen?
STEMCO's solution does NOT provide readings that are displayed on the PeopleNet On Board Computer (OBC) Tire Monitoring Graphic screen shown below; additionally it does NOT provide readings in PeopleNET's web portal named Fleet Manager (pfm). Instead, STEMCO provides a full screen alert when a tire goes low and continues to report the lowest tire pressure on the bottom line of the screen (top line for the legacy classic display); additionally STEMCO provides real-time email alerts and historical reports through its web page (Webbat). 

I just got an email alert from a truck # that is not in our fleet?
This can occur for one of two reasons:
1) Truck # used to be in the fleet - If the truck # used to be in the fleet then the reason is the on board computer was removed from that truck when it was taken out of the fleet and has been reinstalled in another truck but at the time of install the truck # inside the OBC was not reset to the new truck # so it is still reporting in under the old truck #. 
2) Truck # was never in the fleet - When the OBC was originally installed, they report in under a generic set of vehicle #s; if this is not set during the original install then the generic OBC vehicle # is reported instead of the actual truck #.
In either case 1 or 2, the solution is the same. Change the truck # inside the OBC so it will report the correct truck #. Consult the PeopleNET user manual instructions for how to change the vehicle # in the OBC.

Gate Reader Questions

How much does a gate reader cost?
Gate reader costs average $10k – $15k depending on the site.

How long does it take to install a gate reader?
A gate reader can typically be installed in 2 to 3 days with minimal disruption to traffic flow through the gate.

Can I install the gate reader myself?
No… Each installation is custom configured to your needs and requires the skills of a specialized team.

Does STEMCO offer a turnkey installation option for fleets wishing to rapidly deploy the system?
Yes… STEMCO can coordinate an installation plan tailored for your fleet locations and needs to quickly and efficiently complete the deployment for rapid realization of the value equation.

ROI Calculation Questions

Have you validated the fuel savings in your ROI model?
The savings are real. Both the government and TMC have reported that inflated tires save fuel. The amount of savings depends on how far off the set point your tire pressures average and the effectiveness of your current tire program.

Have you validated the tire savings in your ROI model?
As with fuel, the industry has a number of studies on the savings related to proper inflation.

For other questions, read our online resources or contact a STEMCO sales representative.