The pneumatic control unit also contains a sensor that transmits tire-pressure readings to the ECU. An operator control panel allows the driver to select tire-pressure modes to match current conditions. This dash-mounted panel displays current tire pressures, selected modes and system status. When the driver selects a tire-pressure setting, signals from the control panel travel to the electronic control unit to the pneumatic control unit to the wheel valves.
When vehicles are moving faster like on a highway , tire pressure should be higher to prevent tire damage. The CTIS includes a speed sensor that sends vehicle speed information to the electronic control unit. If the vehicle continues moving at a higher speed for a set period of time, the system automatically inflates the tires to an appropriate pressure for that speed. This type of system uses air from the same compressor that supplies air to the brakes. A pressure switch makes sure the brake system gets priority, preventing the CTIS from taking air from the supply tank until the brake system is fully charged.
Here is what happens on the road: The electronic control unit tells the pneumatic control unit to check current pressure and either inflate or deflate the tire to the pressure selected by the driver. If the system determines that inflation is needed, it first checks to make sure that brake pressure reserves are where they should be; if they are, it applies a slight pressure to the wheel valve to allow inflation.
If the tires are overinflated, the system applies a slight vacuum to the wheel valve. When the pneumatic control unit reads that the appropriate pressure is reached, the valve closes.
In this illustration, you can see the pathway that the air travels for inflation or deflation once it gets to the wheel. The tubing runs from the vehicle's air compressor through the wheel hub and then to the tire valve. The hub seals can indeed leak this usually leads to the tires going flat as the air escapes into the hub and out the veny lines.
Give me a call on the cell and I'll explain in more detail. Would I be correct in guessing that in the case of a hub air leak, none or not much hub oil would be sent up the vent lines to possibly enter the diffs, trans or transfer case? Post by civyhummer » Tue Aug 28, am Here's what happened with my civy ' It's a good story that explains the interrelationship between the CTIS, vents, and what can go wrong.
My "new to me" '93 had a bad CTIS leak. So bad that it would pressurize up to about 25psi, but no further. I guess at that point 25psi the pressure and the hole "equalized".
Doing other work on the truck in the garage, I had my hood up. Since it wouldn't go above 25psi, and I had tried this several times, I figured it was safe to leave the compressor on and look for the obvious leak. I was sure at 25psi, I could find it. Well about one minute later there was a big bang and red ATF was everywhere. All over the front of the truck and garage. Turned out to be a clogged actually melted shut breather after they all combined before going to the air filter canister.
That in turn pressurized the breather, pressurizing the tranny and tcase to 25psi or on it's way. That pressure in the tcase launched the tcase disptick into the ceiling and a few quarts of ATF with it. What a mess. I ran dedicated breathers after that incident. Oh yeah, you can find oil in the CTIS lines, and in the breather as well.
Its more trouble than its worth. If you forget to turn off the inflate switch - whoops. The CTIS compressor pushes the air through two proportioning valves which equalize air flow to both front and both rear. At least on my H1, I cannot just inflate front left, I can only do both fronts at the same time - same goes for rear. It would be more handy to just have the compressor on-board and a nice long air hose.
Nice effort, but really the only thing it does really well is leak. Parker offers wheel valves in a variety of sizes and configurations including valves with hose connections as well as flush-mount hose-less versions for use with wheels that have integral air passages.
CTIS provides independent wheel-end control ensuring fail-safe operation in the event of damage to the vehicle or wheel end. The CTIS wheel valve is completely sealed to the atmosphere at the wheel end ensuring reliable deepwater forwarding capability.
Tire venting while deflating is routed back through the pneumatic control unit rather than at the wheel end. The CTIS electronic control unit provides decision making and logic execution. The electronic circuitry is completely sealed in an aluminum enclosure resulting in a rugged environmentally robust package.
Vehicle mobility is improved by reducing tire inflation pressure resulting in a larger tire footprint. This bigger footprint improves traction, reduces wheel slip and allows the vehicle to float across the soft terrain instead of compacting the soil and causing rutting. When returning to improved terrain conditions, a simple push of a button on the driver interface automatically inflates the tires to the appropriate pressure utilizing the onboard air compressor.
Its unique wheel valve design provides the best in class deflate performance while incorporating the non piloted remote venting control strategy preferred by most vehicle manufacturers.
CTIS can deflate tire pressures significantly lower than the competition while operating reliably over a wide range of temperatures and altitudes. The CTIS is insensitive to vehicle installation variables such as wheel-end, the backpressure, and air seal flow.
This results in enhanced fault tolerance as wheel valve shutoff is assured even with kinked, contaminated or restricted airlines. This is a patented wheel valve design that gets the job done faster, resulting in industry precedent-setting deflation rates. The operator interface provides the ability to select four terrain modes:.
Pressing any of the terrain buttons results in the system checking all tire pressures and then automatically adjusting them to pressure targets.
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