Tire Dismounting Guidelines

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1) Remove the valve cap and core and deflate the tire completely. Then remove any balancing weights and position the sensor/valve at the 6 o’clock position. Use the bead shovel to unseat the exterior tire bead. It may be necessary to rotate the valve to the 12 o’clock position and reapply the bead shovel to completely unseat the tire bead. Next, apply the same process to the interior tire bead.
2) Apply lubricant to the outer bead and rim, and align the valve with the left side of the mounting head.
3) Insert the tire tool and lift the outer tire bead onto the mounting head and rotate the table to dismount the outer bead from the rim.
4) Re-position the sensor/valve as in step two and insert the tire tool at the left of the mounting head, and rotate the table to dismount the inner bead. Now, remove the tire.
*Important Reminder
There are two things that can damage the sensor when mounting/dismounting a tire: Tools and the tire beads.

How to Identify Direct TPMS

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1. Is the low tire pressure symbol found on the dashboard? Check for this symbol when starting the ignition.

2. Does the vehicle dashboard have a symbol of the vehicle that highlights tire positions, or a text message that states “check tire pressure” or something familiar?

3. Are the valves stems aluminum and/or secured with nuts? This may indicate a TPM sensor.

To Replace or Not to Replace TPMS?

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The Decision Flowchart helps determine whether a tire pressure monitoring sensor needs to be replaced

 
1) Start: Tire is removed: Remove sensor from wheel and inspect for damage
 
2) Is the sensor housing broken or physically damaged?
 
3) Replace both the sensor and the valve assembly.
 
4) Is the housing coating by any tire sealant?
 
5) For adjustable angle sensors, replace the valve, break-away flange nut, and cap. For fixed angle sensors, replace the valve assembly including the rubber grommet, valve core, and cap. 
 
6) Make sure the new valve cap is securely in place. END.
 

Sensor Removal Instructions

 

1) Unscrew the nut using an 11 or 12 mm socket wrench. Remove the nut and immediately discard the nut if it has a plastic washer attached to it. The adjustable angle sensor has a break-away feature inside the nut which is used to set the torque on the screw. This is a one time use feature. For this reason a nut with a plastic washer cannot be reused. 
 
 
2) Remove the sensor and valve from the rim and inspect the sensor for any physical or sealant damage. 
 

Fixed Angle TPMS Sensor Mounting Guidelines

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1) Insert the sensor-valve unit through the valve hole of the rim.
 
2) Hold the sensor feet and the rubber grommet against the rim surface.
 
3) Insert the nut over the valve stem. 
 
 
1) Begin to tighten the nut using a 12mm deep socket. Continue to tighten the nut until 35 lbf.in or 4.0 Nm, the recommended final torque setting. 
 

Adjustable Angle TPMS Sensor Mounting Guidelines

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1) Insert the screw into the slotted hole of the sensor: Using an index finger, insert the screw into the slotted hole of the sensor housing, and check that the flats of the square part of the screw fit securely.
2) Assemble the valve to the screw: Turn the valve stem 3 to 4 full rotations.
3) Slide the valve stem through the valve hole of the rim: Hold the sensor feet against the drop center of the rim and the grommet against the seal surface.
4) Insert the nut over the valve stem: By hand or with an 11mm socket wrench begin to tighten the nut 3 to 4 rotations.
5) Continue tightening the nut: Using a Torque wrench, continue tightening the nut.
6) Valve/screw attachment is completed: The nut’s internal flange is designed to break away at approximately 20 lbf.in or 2.2 Nm. The screw and the valve stem are now secured, but the sensor is not secured.
7) Tighten the nut to the final torque: Continue to tighten the nut to the final torque (35 lbf.in or 4.0Nm). At this point, the valve/wheel attachment is completed.

Other Energy Options Sought as the End of TPMS Battery Life Nears

Other Energy Options Sought as the End of TPMS Battery Life Nears

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First generation TPMS sensors are nearing the end of their battery life, so it’s a perfect time to take a look at the new technologies being developed to increase TPMS sensor service life without compromising performance.

Direct TPMS is currently the most accurate method of obtaining tire pressures during vehicle operation. Compared to indirect systems, the in-wheel tire pressure sensor has a higher degree of sensitivity to pressure changes, allowing accurate feedback to the driver.

Still in its infancy, TPMS technology continually evolves as a variety of manufacturers vie for part of a global market projected to reach $3 billion by 2017. Part of this will be driven by Europe, as mandatory TPMS comes on-stream there in the not too distant future. And wait until China, with its massive car parc, goes to mandatory TPMS.

As we have previously discussed, first generation TPMS sensors are nearing the end of their battery life, so it’s a perfect time to take a look at the new technologies being developed to increase TPMS sensor service life without compromising performance. Some of these might even serve to improve performance.

Current TPMS technology utilizes either 3-volt lithium ion or 1.25-volt nickel metal-hydride batteries to energize the sensors. Sensors generally transmit pressure data to the on-board computer every few minutes so as to maximize battery life, but this low sampling rate could be detrimental in a rapid air-loss situation.

Sensors also go into “sleep mode” when the vehicle is parked to minimize energy loss, and re-awaken after the vehicle has been driven for a few miles. It is possible after vehicle startup that a low-pressure situation will not be apparent until several miles down the road.

It seems the ideal direct TPMS sensor would have a lifetime energy supply and provide a higher frequen­­cy sampling rate. Having to never worry about battery failure certainly would be an acceptable feature from the consumer’s point of view. And high frequency sampling rates currently exist in the racing world.

For racing applications, Beru manufactures TPMS sensors that also measure internal tire temperatures using infra-red technology at a sampling rate of 1 cycle per second, but that is one end of the extreme spectrum where cost and battery life are of no real concern. To have a continuous supply of electrical power, the TPMS industry is turning to energy harvesters for a practical solution.

Energy Options
Piezoelectricity looks to be the leading technology of energy harvesting for TPMS applications, as it relies on mechanical stress or vibration to produce electrical energy. A piezoelectric material creates an electrical charge when deformed. The simple rotation and inherent vibration of a rolling tire serves as a practical method of converting mechanical energy into electrical energy, which can then be stored in a capacitor to power a TPMS sensor.

PZT (lead zirconium titanate), a man-made ceramic compound, ap­pears to be the most popular choice as an energy harvesting material. When subjected to vibration or deformation, PZT creates a relatively high-energy output. But wait – there’s that toxic word, lead, trying to find its way back into the tire/wheel assembly. Fortunately, there has been a resur­gence to develop lead-free piezoelectric materials because of the toxicity concerns of lead-containing devices.

Having a constant energy supply would allow for higher sampling rates, and rather than waiting five minutes between pressure data readings, there would be enough power to transmit pressure readings every minute or so. Used in conjunction with a capacitor to store electrical energy, instantaneous pressure data transmission upon vehicle startup could be realized, eliminating the built-in inoperative feature currently in use.

The success of piezoelectric materials will depend on finding a low-cost method of mass production to make them attractive as a replacement for traditional batteries. Most vehicle manufacturers are cost sensitive, and I believe they will determine when the industry will change over to piezo­electric power.

Practical Concerns
But even at this writing, technology continues to march on. One major disadvantage of the current direct TPMS sensor mounted at the valve hole is its location. An improperly trained technician can easily destroy a sensor during a basic tire dismounting or mounting. Introduce conventional-looking snap-in valves to the TPMS sensor and the margin for error increases even more.

It would be more advantageous to have the pressure sensor attached to the tire profile, preferably during the manufacturing process, so as to make it an integral part of the tire.

Unfortunately, the inherent brittleness of ceramic in PZT does not lend itself to this application. Ad­vanced Cer­am­etrics in Lam­bertville, N.J., has created a patented viscous suspension spinning process (VSSP) that transforms any ceramic material into a fiber form, giving it a degree of flexibility. This technology would give materials like PZT the robustness necessary for application to the tire’s inside surface.

Along a similar design application, U.K.-based Piezotag Ltd. has successfully de­veloped a piezoelectric-powered TPMS sensor that mounts on the inside of the tire. The disc-like device is bonded to the tire innerliner and requires no battery for power or initiators in the wheel well for tire position identification.

The housing of the sensor was designed to protect the delicate nature of the piezo ceramic, and product testing has shown positive results for durability throughout the life of the tire.

The current drawback is the labor involved in mounting the sensor as compared to the current method of snap-in or clamp-in sensors at the valve hole. Again, the OEMs will shape the future of this TPMS sensor option.

TPMS has quickly become a four-letter word – I mean “acronym” – thrust upon the automotive world to help improve vehicle safety. The system is necessary to aid drivers with tire air pressure maintenance.

Automotive sensors have been around for decades to monitor a variety of vehicle systems such as engine oil pressure, cooling system temperature and fuel level. It is ironic that the most critical component of a vehicle that has greatest impact on vehicle safety – its tires – has become one of the last to incorporate sensors and the one with the greatest push-back by so many in the industry.

To complicate matters, such a safety-critical system was designed to rely on batteries, and everyone involved knew the day would come when the batteries would run dry, creating inoperative system and flummoxed drivers.

A true “safety system” needs to have maximum reliability throughout the vehicle’s service life. The current battery technology defeats the purpose of this safety system, but new technology is around the corner to make TPMS the safety system its creators envisioned. If only we could get automaker buy-in.

Source: Tire Review – Rudy Consolacion  

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