BONNET 7W8545 - Caterpillar

Tamper Screed with Optional Extensions
Illustration 14 g03812344
Screed Heat Control Electrical Schematic
(1) Inverter connection
(2) Screed power module
(3) Right main tamper bar
(5) Right extender screed plate
(6) Right extender tamper bar
(7) Hazardous voltage connector
(8) Right extension screed plate
(9) Right extension tamper bar
(10) Heater ECM
(11) Tractor connection
(12) Left main screed plate
(13) Left main tamper bar
(14) Left extender tamper bar
(15) Left extender screed plate
(16) Extension high voltage harness
(17) Extension high voltage connector
(18) Left extension tamper bar
(19) Extension resistor
(20) Left extension screed plate
(21) Extension low voltage connector
(22) Extension low voltage harness
(23) Extension low voltage connector The electrical system for the tamper screed is similar to the vibratory screed. Tractor connection (11) provides 24V power to the screed electrical system. Inverter connection (1) supplies hazardous voltage power to screed power module (2) for the heaters. CAN communication between the screed and the tractor are the same. Refer to the vibratory schematic for details.Similar to the vibratory screed, tamper screed configuration settings from the machine operator stations are stored in the memory of the screed ECM. The software flashed in this ECM also determines the tamper configuration of the screed. When optional bolt-on extensions are installed, the configuration of the extensions is determined with resistors.Each bolt-on extension has extension resistor (19) installed. The ohm values of these resistors vary by extension size as follows:
Extension length = 0.25 M (0.82 ft.) - 7.87 kilo-ohms
Extension length = 0.75 M (2.46 ft.) - 25.5 kilo-ohms
Extension length = 1.25 M (4.10 ft.) - 16.5 kilo-ohmsThe total resistance value determines the quantity of extensions installed. This information also determines the heater element requirements added. A maximum of two extensions can be installed.Note: Extension low voltage harness (22) is required to connect the bolt-on extensions. The extension resistance signal and various other signals are transmitted through this harness.The resistance value is monitored by screed power module (2). The right extension configuration value is read at terminal "MR-C3-23". The left extension configuration value is read at terminal "MR-C3-31".The resistance information is sent to heater ECM (10). The heater ECM uses the information for calculating power requirements for the additional heater elements. The ECM also distributes the extension configuration to the screed ECM and the operator displays.The standard equipped tamper screed contains 12 heater elements in the following locations:
Two elements heat right main screed plate (3)
One element heats right main tamper bar (3)
Two elements heat right extender screed plate (5)
One element heats right extender tamper bar (6)
Two elements heat left main screed plate (12)
One element heats left main tamper bar (13)
Two elements heat left extender screed plate (15)
One element heats left extender tamper bar (16)For the tamper screed, each optional bolt-on extension contains two heater elements. One element heats the extension screed plate and one element heats the extension tamper bar. Each extension also contains a temperature sensor.Note: The vibratory bolt-on extensions contain only one heater element used to heat the extension screed plate.When the heat system is turned on, the overall screed configuration information is communicated on the CAN lines. The requested heat system