1. A transmission park-brake system, comprising:
a transmission park brake;
a solenoid;
first, second and third pressure sources;
a servo valve for disengaging the park-brake using the first and second pressure sources, holding the park-brake disengaged using a force produced by the solenoid and one of the first and second pressure sources, and engaging the park-brake using the third pressure source.
2. The transmission park-brake system of claim 1, wherein:
the servo valve includes a first surface having a first area to which pressure of the first pressure source is applied to the servo valve when a first control element of a transmission is engaged; and
the servo valve includes a second surface having a second area to which pressure of the second pressure source is applied to the servo valve when a second control element of the transmission is engaged.
3. The transmission park-brake system of claim 2, wherein:
the servo valve includes a third surface having a third area to which pressure of the third pressure source is applied to the servo valve tending to engage the park brake.
4. The transmission park-brake system of claim 1, wherein:
the servo valve includes a first surface having a first area to which pressure of the first pressure source is applied to the servo valve tending to disengage the transmission park brake when a first control element of a transmission is engaged to produce alternately reverse gear and one of a first set of forward gears of the transmission; and
the servo valve includes a second surface having a second area to which pressure of the second pressure source is applied to the servo valve tending to disengage the transmission park brake when a second control element of the transmission is engaged to produce alternately reverse gear and one of a second set of forward gears of the transmission.
5. The transmission park-brake system of claim 1, wherein the solenoid applies a force to the servo valve tending to resist engagement of the transmission park brake.
6. The transmission park-brake system of claim 1, wherein the servo valve includes a spring that applies a force to the servo valve tending to engage the transmission park brake.
7. A transmission park-brake system, comprising:
a transmission park brake;
a solenoid;
first, second and third pressure sources;
a servo valve including a spool alternately releaseably latchable to the solenoid, connected to the park-brake, and formed with a surface to which pressure of the first pressure source is applicable, a second surface to which pressure of the second pressure source is applicable, and a third surface to which pressure of the third pressure source is applicable.
8. The transmission park-brake system of claim 7, wherein:
pressure of the first pressure source is applied to the surface when a first control element of a transmission is engaged;
pressure of the second pressure source is applied to the second surface when a second control element of the transmission is engaged; and
pressure of the third pressure source is applied to the third surface when the transmission is driven by a power source.
9. The transmission park-brake system of claim 7, wherein:
pressure of the first pressure source when applied to the surface tends to disengage the transmission park brake;
pressure of the second pressure source when applied to the second surface tends to disengage the transmission park brake; and
pressure of the third pressure source when is applied to the third surface tends to engage the transmission park brake.
10. The transmission park-brake system of claim 7, further comprising a spring that applies a force to the spool tending to engage the transmission park brake.
11. The transmission park-brake system of claim 7, further comprising a spring that applies a force to the spool that engages the transmission park brake when pressure of the first, second and third pressure sources is absent.
12. A method for operating a transmission park-brake system, comprising:
disengaging the transmission park-brake using first and second pressure sources;
holding the transmission park-brake disengaged using a force produced by a solenoid and one of the first and second pressure sources; and
engaging the transmission park-brake using a third pressure source.
13. The method of claim 12, further comprising using a force produced by a spring to engage the transmission park brake when pressure produced by the first, second and third pressure sources is absent.
14. The method of claim 12, further comprising using a force produced by a spring and using the third pressure source to engage the transmission park brake when pressure of the pressure produced by the first and second pressure sources is absent.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of transferring data over a network, said method comprising the steps of:
establishing a communication link for transfer of print data from a terminal to a printer system over the network, upon receipt of a print request from the terminal,
wherein the network is a wide area network.
2. The method of claim 1 wherein the network is an IMS network having a wireless network portion, and the terminal is a wireless unit.
3. The method of claim 2 wherein the wireless unit is at a first location, and the printer system is at a second location remote from the first location, said printer system including at least one printer.
4. The method of claim 2 wherein the printer system is configured to automatically print at least one hard copy document subsequent receipt of the print data from the terminal over the network.
5. The method of claim 4 further comprising:
generating billing data relating to the transfer of the print data from the terminal to the printer system, said billing data being associated with the terminal.
6. The method of claim 4 wherein the communication link is established based at least in part on (i) at least one status message received from the printer system and on (ii) the print request received from the terminal, said status message indicating a status of the printer system for automatically printing the at least one hard copy document, and said print request including an identifier of the printer system for associating the print request with the status message.
7. The method of claim 6 further comprising:
generating billing data relating to the transfer of the print data from the terminal to the printer system, said billing data being associated with the terminal.
8. The method of claim 6 wherein the printer system identifier is a network URL.
9. The method of claim 6 further comprising:
determining if the terminal is authorized to transfer said print data to the printer system based at least in part on the print request message.
10. The method of claim 6 further comprising:
transmitting a network address of the printer system to the terminal, said network address comprising at least one of a network IP address and a network port of the printer system, wherein the print data is addressed to said at least one of the network IP address and the network port of the printer system.
11. The method of claim 6 further comprising:
registering said printer system and said terminal for transfer of said print data over the network, based at least in part on registration request communications received from the printer system and terminal.
12. A method of transferring data over a network, said method comprising the steps of:
determining whether a print request received from a terminal over the network is an authorized print request; and, if so,
automatically printing at least one hard copy document based on print data received from the terminal, wherein the network is a wide area network.
13. The method of claim 12 wherein the network is an IMS network having a wireless network portion, and the terminal is a wireless unit, said wireless unit being at a first location remote from a second location of where the hard copy document is printed.
14. The method of claim 13 wherein the determination of whether the print request is an authorized print request is based at least in part on an identifier included in the print request message, said identifier being associated with at least one of the terminal and a user of the terminal.
15. The method of claim 13 further comprising:
registering with the IMS network for receiving print requests and print data over the IMS network.
16. The method of claim 13 further comprising:
periodically transmitting status messages to the IMS network, said status messages relating to the availability of automatic printing of hard copy documents upon receipt of authorized print requests over the network.
17. A method of transferring data over a network, said method comprising the steps of:
transmitting a print request message over the network, said print request message including an identifier associated with a printer system; and
transmitting print data to the printer system over the network, said print data including a network address of the printer system received in a print request answer message,
wherein the network is a wide area network.
18. The method of claim 17 wherein the network is an IMS network having a wireless network portion, and wherein the print request message is transmitted wirelessly over the wireless network portion of the IMS network.
19. The method of claim 18 further comprising:
transmitting hash data associated with the print data for reassembly of the print data by the printer system.
20. The method of claim 18 further comprising:
registering with the IMS network for transmission of print data to the printer system.