Advantages of a Dedicated PTO
The Engine Control Module (ECM) provides several options in order to enhance vehicles that require control of the engine speed for vocational applications. The vocational applications include the following applications: cement mixers, refuse packers, bulk haulers, utility trucks, fire trucks and applications that require the control of the engine rpm for the operation of specialized equipment.
The programmable input and output features of the dedicated PTO parameters provide a significant increase in the capability of the engine and of the usage of the engine.
An electronically controlled engine eliminates the need for the following items: mechanical control cables, air cylinders, electric solenoids and linkages and connections. The dedicated PTO provides a simple installation. The cruise control switches that are in the cab and the circuit for the accelerator pedal position are left unaffected.
Features of the Dedicated PTO
There are several features of the dedicated PTO:
- The dedicated PTO reduces the alteration of the cab wiring or the dedicated PTO eliminates the alteration of the cab wiring.
- The dedicated PTO has multiple speed control by using the "PTO Engine RPM Set Speed Input A" and "PTO Engine RPM Set Speed Input B".
- The dedicated PTO has two speed controls that require the PTO On/Off circuit.
- The dedicated PTO has an accelerator position sensor that is remote. This sensor enables the system to control engine rpm with variable speeds from a remote location.
- The dedicated PTO has reduced engine noise levels during PTO operation. The reduced engine noise levels are compared to a mechanical engine PTO.
Customer Programmable Parameter Options
There are many customer programmable parameter options:
"PTO Configuration" - The "PTO Configuration" determines the input/output configuration that is used for the Dedicated PTO operation.
"PTO Top Engine Limit" - The "PTO Top Engine Limit" provides a parameter in order to limit the engine rpm during PTO operation.
"PTO Engine RPM Set Speed" - The "PTO Engine RPM Set Speed" provides a set point for the engine rpm for the PTO.
"PTO Engine RPM Set Speed A" - This provides a programmable engine speed set point that is actuated by a dedicated switch circuit. "PTO Engine RPM Set Speed A" must be programmed to J1/P1:46 Input 7. This requires an additional switch to be installed in order for this feature to function. JUL99 or later Personality Modules
"PTO Engine RPM Set Speed B" - This provides a second programmable engine speed set point that is actuated by a second dedicated switch circuit. "PTO Engine RPM Set Speed B" must be programmed to J1/P1:7 Input 4 or J1/P1:23 Input 19. This requires an additional switch to be installed in order for this feature to function. JUL99 or later Personality Modules
"PTO to Set Speed" - The "PTO to Set Speed" function requires only one circuit (PTO On/Off Switch) to provide two speed controls. The "PTO to Set Speed" function provides three-speed controls by using the PTO On/Off Switch and the Set/Resume Switch.
"Maximum PTO Enable Speed" - The "Maximum PTO Enable Speed" provides a parameter in order to prevent the engine from entering PTO Mode at a high rpm range.
"PTO Cab Throttle RPM Limit" - The "PTO Cab Throttle RPM Limit" provides a parameter in order to limit the rpm from the accelerator pedal position sensor in the cab during PTO operation. This parameter is intended to prevent engine overspeed when the dedicated PTO is used.
"PTO Kickout Vehicle Speed Limit" - "The PTO Kickout Speed Limit" determines the maximum vehicle speed for setting or maintaining a set engine rpm in PTO mode.
"Maximum PTO Vehicle Speed Limit" - The "Maximum PTO Vehicle Speed Limit" determines the maximum vehicle speed during PTO operation. (The "Maximum PTO Vehicle Speed Limit" parameter is for Medium Duty Engines.)
"Torque Limit" - The "Torque Limit" reduces the engine torque during PTO operation. The "torque limit" will also reduce the engine torque when the Torque Limit Switch is in the ON position for temporary protection of equipment.
"PTO Shutdown Time" - The "PTO Shutdown Time" is a programmable time. If the engine is in PTO mode, then the "PTO Shutdown Time" will shut down the engine when the time limit expires.
"PTO Activates Cooling Fan" - The "PTO Activates Cooling Fan" can be programmed so that the cooling fan will operate during PTO operation.
"Input 4" -. Input 4 J1/P1:7 provides a parameter for a Torque Limit switch when torque limiting is desired for temporary protection of equipment. This is regardless of the position of the PTO On/Off switch. " Input 4" can also be used for "PTO Engine Set Speed B"."Input 4" is for Medium Duty Engines.
"Input 5" - Input 5 J1/P1:47 provides a parameter for an Ignore Brake/Clutch switch when mobile use of the vehicle is desired with a set engine rpm. The brake and the clutch are not required in order to disengage the engine rpm set speed. "Input 5" is for Medium Duty Engines.
"Input 7" - Input 7. J1/P1:46 can be programmed to "PTO Engine RPM Set Speed Input A" in order to provide a dedicated circuit for the PTO operation at a programmed speed when the PTO On/Off switch is ON. Input 7 is for Medium Duty Engines.
"Input 19" -. Input 19. J1/P1:23 is programmable to "PTO Engine RPM Set Speed Input B" in order to provide a second dedicated circuit for the operation at a programmed speed when "PTO Engine RPM Set Speed Input A" is OFF and the PTO On/Off switch is ON. "Input 19" is for Medium Duty Engines.
Note: Inputs (4,5, 7 and 19) are not used on the OCT01 or newer personality modules. The Caterpillar Electronic Technician (ET) will not display inputs. Cat ET will display the ECM terminal or the parameter that is used.
Additional Features of the Dedicated PTO
- The engine exhaust brake that is controlled by the ECM is disabled when the PTO On/Off circuit is in the ON position.
- When the PTO On/Off switch is in the ON position, the Idle Shutdown feature is disabled.
- Two terminal connector and wiring is standard on all GM applications. Two terminal connector and wiring is standard for the PTO On/Off Switch. Two terminal connector and wiring is standard for the PTO Interlock Switches.
- The PTO Shutdown Timer reduces driver abuse. Driver abuse is placing the truck in PTO mode in order to disable the idle shutdown time.
Definition of Power Take-Off (PTO)
The dedicated PTO is an engine rpm control that is initiated through an On/Off circuit. The circuit is connected to Input 1 (terminal 56) of the ECM Vehicle Harness Connector J1/P1. Engine rpm control that is initiated through the Cruise Control On/Off switch is referred to as Extended Idle. Engine rpm control that is initiated through the Fast Idle Enable Switch is referred to as Fast Idle.
The Four Programmable PTO Configurations
Off - The functions for the dedicated PTO are not available.
Cab Switches - The cruise control Set/Resume switch and the Accelerator Pedal are used to control the engine rpm. A dedicated PTO On/Off switch is required. Refer to Illustration 1.
Remote Switches - The Set/Resume switch for the remote PTO is used to control the engine rpm. The remote switches ignore all of the cab controls. An On/Off switch for the dedicated PTO is required. Refer to Illustration 2.
Remote Throttle - The remote throttle is used in order to control the engine rpm. The remote throttle will ignore all of the cab controls. An On/Off switch for the dedicated PTO is required. Refer to Illustration 3.
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| Illustration 1 | g01114028 |
PTO configuration for cab switches (1) Cruise Control Set/Resume Switch (2) PTO On/Off Switch (3) PTO Switch On Lamp | |
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| Illustration 2 | g01114043 |
PTO configuration for remote switches (4) PTO Switch On Lamp (5) PTO Set/Resume Switch (6) PTO On/Off Switch (7) PTO Switch On Lamp | |
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| Illustration 3 | g01114048 |
PTO configuration for remote throttle (8) PTO Switch On Lamp (9) PTO On/Off Switch (10) PTO Set/Resume Switch (11) PTO Switch On Lamp (12) Remote Throttle for the PTO | |
One Speed Control with One Circuit
One speed control with one circuit provides an optional PTO Set Speed for applications that require only one speed above low idle. The following components are required: PTO On/Off Switch, PTO Interlock Switches and PTO Switch On Lamp(s).
Two Speed Control with Three Circuits
The two speed control with three circuits has two set speeds above low idle. The two set speeds that are above the low idle engine rpm are the PTO to Set Speed and the PTO Top Engine Limit. The following components are required: PTO On/Off Switch, PTO Interlock Switches, Cruise Control or Remote Set/Resume Switch and PTO Switch On Lamp(s).
Variable Speed Control that uses "Remote Switches"
The following components are required: PTO On/Off switch, PTO interlock switches, PTO Set/Resume switch and PTO switch On lamp
Variable Speed Control That uses an Input for the Remote Accelerator Position Sensor
The following components are required: PTO On/Off Switch, PTO Interlock Switches, Cruise Control Switch or Remote Set/Resume Switch and Remote Hand Accelerator or an Accelerator Pedal Assembly that is equipped with a Accelerator Position Sensor that is supplied by Caterpillar.
Multiple Speed Control That Uses Dedicated Switch Inputs
This function can be used in conjunction with other features that are used to control engine speed. The function is available for the three configurations for the PTO. The following components are required: PTO On/Off Switch, PTO Interlock Switches and switch for the "PTO Engine RPM Set Speed Input A". The switch for the "PTO Engine RPM Set Speed Input B" can be used in addition to the switch for the "PTO Engine RPM Set Speed Input A".
Engine RPM Control That Uses Switches Instead of a Control That Uses An Accelerator Position Sensor
This function uses switches in order to control engine rpm. Switches are also recommended if the operator of the PTO will be frequently varying the engine rpm. Switches are recommended if the operator of the PTO will not have a free hand or a free foot in order to operate the accelerator.
Differences Between Fast Idle and Dedicated PTO Operation
Note: This option is not available on all engines.
The following differences are between the fast idle and the dedicated PTO:
- Fast Idle is intended for cab control of the engine speed. The dedicated PTO can be set up for control in the cab or for remote control of engine speed during PTO operation.
- Fast Idle requires a single momentary switch to select the programmed engine speed(s). The dedicated PTO can be as simple as a single two-position switch. The two positions are the ON position and the OFF position. The dedicated PTO can also require combinations of two-position switches and momentary switches.
- The dedicated PTO provides several options: programmable engine rpm limits, set points, bump rates, ramp rates and programmable torque limit. These features are not available for Fast Idle control.
- The ramp rate for Fast Idle rpm is fixed and this rate can not be adjusted.
- Fast Idle requires a momentary switch. Fast Idle can not be used with a typical PTO system that requires two-position switches. The momentary switch can not be operated hydraulically. The momentary switch can not be operated by air. The momentary switch can not be a position limit switch that is integrated into the PTO operation.
Fast Idle Operation That Has One or Two Speed Control with One Circuit
- This function provides an optional set speed(s) for applications that require only one or two speeds above low idle.
- A momentary Fast Idle Enable Switch and a Fast Idle Enabled Lamp are required.
Recommended Information for Operator of the PTO
Ensure that the operator understands the operation of the engine and the components for the PTO operation. Ensure that the operator understands the operation before attempting to install the switches before the parameters are programmed. The installation questionnaire will make the installation easier to understand. The installation questionnaire will help the installer understand the options that are needed.
Question (1) through question (8) should be asked before starting the installation procedure. The remaining questions may be asked after the installation is completed. This will help to fine tune the programming and other system components. Refer to the information for programmable parameters that is found in "Programmable Parameters Available Ranges, Options, and Default Settings". For more information, refer to Special Publication, LEXT0023, "Programming CAT Electronic Truck Engines". Also refer to Special Publication, LEBT9390, "Electrical and Electronic Application and Installation Guide".
Complete the following information once the installation is complete:
- Programmed Parameter Information Sheet for the Operator of the PTO
- Instructions for the Operator of the PTO
- Diagrams for Switches and Components that are used for the Installation of the PTO
The information that is recorded should be explained to the operator of the PTO. The information that is recorded should be left in the cab glove box. This will allow the operator of the PTO to review the configuration of the truck and the PTO. This will allow the service technician to troubleshoot any suspected problems that relate to the installation.
Installation Questionnaire
Refer to the Electronic PTO Installation and Applications Guide for Electronic Engines, "PTO Parameters - Program" for the installation and programming that is based on the information on the Questionnaire Response.
| Questions | Response |
| Determine the location of the controls inside the cab for the PTO. Determine the location of the controls outside the cab for the PTO. Determine if control of the engine rpm is required from both the cab and outside of the cab. Determine if the operator of the PTO will be continually varying engine rpm. Determine if a hand accelerator or a foot accelerator will be used. |
|
| Determine the "Maximum PTO Vehicle Speed". Determine if the PTO will require the use of the clutch and the service brakes. Determine that the engine rpm must be maintained when the clutch and service brakes are used. |
|
| Determine the maximum torque of the equipment when the PTO On/Off circuit is ON. | |
| Determine the necessity of a torque limit when the PTO On/Off circuit is in the OFF position. Example Determine that a torque limit is needed in order to reduce the torque for the driveline. |
|
| Determine if one or more fixed engine rpm above low idle is required. Determine the first engine rpm. Determine the second engine rpm. Determine the necessity in order for the engine to accelerate to the first engine rpm when the PTO On/Off switch is turned to the ON position. |
|
| Determine the operating speed points. | |
| Determine the maximum operating engine rpm for the equipment. Determine if the accelerator pedal rpm should be limited. This will occur only if the control of the engine rpm is from the cab. |
|
| Determine the acceleration rate that is required in order for the engine to reach the set point for the engine rpm. Determine the rate of deceleration that is required in order for the engine to decelerate from the set point for the engine rpm. | |
| Ask the following question ONLY if the vehicle uses the ECM to turn the engine cooling fan ON. If necessary, contact the OEM of the vehicle for more information. Determine the minor fluctuations in engine rpm that are caused by the engine cooling fan that is cycling ON and OFF. Determine if this will cause a pump problem or other system problems. |
Programmed Parameter Information Sheet for the Operator of the PTO
Use the following table to fill in the programmed parameters once the installation is complete. Otherwise, print a copy of the engine configuration by using Cat ET.
Note: Table 2 refers to the Heavy Duty Engines. C-10, C11, C-12, C13, 3406E, C15, C-15, C-16, and C-18
| "Selected Engine Rating" | |
| "Rating Number" | |
| "Muiltitorque Ration" | |
| "ECM Identification Parameters" | |
| "Vehicle ID" | |
| "Truck Manufacturer Parameters" | |
| "Truck Manufacturer" JUL99 and newer Personality Modules |
|
| "Vehicle Speed Parameters" | |
| "Vehicle Speed Calibration" | |
| "Vehicle Speed Cal (J1939 - Trans)" | |
| "Vehicle Speed Cal (J1939 - ABS)" | |
| "Vehicle Speed Limit" (VSL) | |
| "VSL Protection" | |
| "Tachometer Calibration" | |
| "Soft Vehicle Speed Limit" | |
| "Low Speed Range Axle Ratio" | |
| "High Speed Range Axle Ratio" | |
| "Cruise Control Parameters" | |
| "Low Cruise Control Speed Set Limit" | |
| "High Cruise Control Speed Set Limit" | |
| "Engine Retarder Mode" | |
| "Engine Retarder Minimum VSL Type" | |
| "Engine Retarder Minimum Vehicle Speed" | |
| "Auto Retarder in Cruise (0=Off)" | |
| "Auto Retarder in Cruise Increment" | |
| "Cruise/Idle/PTO Switch Configuration" | |
| "Soft Cruise Control" | |
| "Adaptive Cruise Control Enable" | |
| "Idle Parameters" | |
| "Idle Vehicle Speed Limit" | |
| "Idle RPM Limit" | |
| "Idle/PTO RPM Ramp Rate (rpm/sec)" | |
| "Idle/PTO Bump RPM" | |
| "Dedicated PTO Parameters" | |
| "PTO Configuration" | |
| "PTO Top Engine Limit (TEL)" | |
| "PTO Engine RPM Set Speed" | |
| "PTO Engine RPM Set Speed A" | |
| "PTO Engine RPM Set Speed B" | |
| "PTO to Set Speed" | |
| "Maximum PTO Enable Speed" | |
| "PTO Cab Controls RPM Limit" | |
| "PTO Kickout Vehicle Speed Limit" | |
| "Max PTO Vehicle Speed" | |
| "Torque Limit" | |
| "PTO Shutdown Time" | |
| "PTO Shutdown Timer Maximum RPM" | |
| "PTO Activates Cooling Fan" | |
| "Engine and Gear Parameters" | |
| "Lower Gears Engine RPM Limit" | |
| "Lower Gears Turn Off Speed" | |
| "Intermediate Gears Engine RPM Limit" | |
| "Intermediate Gears Turn Off Speed" | |
| "Gear Down Protection RPM Limit" | |
| "Top Engine Limit (TEL)" | |
| "Top Engine limit with Droop" | |
| "Low Idle Engine RPM" | |
| "Transmission Style" | |
| "Eaton Top 2 Override with Cruise Switch" | |
| "Top Gear Ratio" | |
| "Top Gear Minus One Ratio" | |
| "Top Gear Minus Two Ratio" | |
| "Governor Type" | |
| "Input Selections" | |
| "Torque Limit Switch" | |
| "Ignore Brake/Clutch Switch" | |
| "PTO Engine RPM Set Speed A" | |
| "PTO Engine RPM Set Speed B" | |
| "Remote PTO Set Switch" | |
| "Remote PTO Resume Switch" | |
Note: Table 3 refers to the Medium Duty Engines. 3126B, 3126E, C7, and C9
| "Selected Engine Rating" | |
| "Rating Number" | |
| "ECM Identification Parameters" | |
| "Vehicle ID" | |
| "Truck Manufacturer Parameters" | |
| "Truck Manufacturer" "Truck Model Type" |
|
| "Vehicle Speed Parameters" | |
| "Vehicle Speed Limit (VSL)" | |
| "VSL Protection" | |
| "Soft Vehicle Speed Limit" | |
| "Cruise Control Parameters" | |
| "Low Cruise Control Speed Set Limit" | |
| "High Cruise Control Speed Set Limit" | |
| "Engine Brake Mode" | |
| "Cruise/Idle/PTO Switch Configuration" | |
| "Auto Retarder in Cruise (0 = OFF)" | |
| "Idle Parameters" | |
| "Idle Vehicle Speed Limit" | |
| "Idle RPM Limit" | |
| "Idle/PTO RPM Ramp Rate (rpm/sec)" | |
| "Idle/PTO Bump RPM" | |
| "Fast Idle RPM 1" | |
| "Fast Idle RPM 2" | |
| "Warm Up Mode Idle Speed" | |
| "Dedicated PTO Parameters" | |
| "PTO Configuration" | |
| "PTO Top Engine Limit" | |
| "PTO Engine RPM Set Speed" | |
| "PTO Engine RPM Set Speed A" | |
| "PTO Engine RPM Set Speed B" | |
| "PTO to Set Speed" | |
| "Maximum PTO Enable Speed" | |
| "PTO Cab Throttle RPM Limit" | |
| "PTO Kickout Vehicle Speed" | |
| "Maximum PTO Vehicle Speed Limit" | |
| "Torque Limit" | |
| "PTO Shutdown Time" | |
| "PTO Activates Cooling Fan" | |
| "Exhaust Brake Warm Up Enable" | |
| "Engine and Gear Parameters" | |
| "Top Engine Limit" | |
| "Low Idle Engine RPM" | |
| "Transmission Style" | |
| "AT/MT/HT Part Throttle Shift Speed" | |
| "Input Selections" | |
| "Input 4 - Torque Limit Switch or PTO Engine RPM Set Speed B" JUL99 |
|
| "Input 5 - Ignore Brake/Clutch Switch" MAR98 |
|
| "Input 7 -PTO Engine Set Speed A" JUL99 |
|
| "Input 19 -PTO Engine Set Speed B" JUL99 |
|
| "Torque Limit Switch" OCT01 and newer Personality Modules |
|
| "Ignore Brake/Clutch Switch" OCT01 and newer Personality Modules |
|
| "PTO Engine Set Speed A" OCT01 and newer Personality Module |
|
| "PTO Engine Set Speed B" "OCT01" and newer Personality Modules |
|
Instructions for the Operator of the PTO
| Question | Response |
| The following interlocks must be set before the engine can be operated for PTO purposes. For example, the parking brake must be engaged and the transmission must be placed in the neutral position. |
|
| Determine the location of the PTO On/Off switch. Determine the labeling of the switch. | |
| Determine the maximum vehicle speed while the PTO is in operation. NOTE: Exceeding the maximum vehicle speed will cause the engine to exit the PTO set speed. The engine will then return to low idle. |
|
| Determine if the PTO is set up in order to allow the use of the clutch and service brakes with an engine rpm set speed. Determine the PTO mode vehicle speed limit that is required for the operation of the PTO. If the answer is yes, then determine the location of the switch that allows this operation. Determine the labeling of the switch. |
|
| Determine the acceleration rate that is required in order for the engine to reach the set point for the engine rpm. Determine the rate of deceleration that is required in order for the engine to decelerate from the set point for the engine rpm. | |
| Determine if only one or two engine rpm above low idle are necessary. Determine the first engine rpm. Determine the second engine rpm. |
|
| Determine if the installation is configured for engine acceleration to increase to a desired engine rpm. This should happen when the PTO On/Off switch is turned to the ON position. | |
| Determine the necessity that involves the cooling fan that runs constantly when the control that is for the cooling fan is active. | |
| Determine the location of the PTO Switch On Lamp. Determine the labeling of the switch. | |
| Determine the programming of the PTO Shutdown Timer. | |
| Determine the programming of the "PTO Torque Limit". |
Truck Installation Diagram for The Switches and The Components
Follow the steps below once the installation is complete:
- Locate the following items and create a sketch of these items: switches, sensors and lamps. Refer to the Electronic PTO Installation and Applications Guide for Electronic Engines, "The Four Programmable PTO Configurations" for the installation and programming that is based on the information on the Questionnaire Response.
- Provide a copy of the appropriate diagrams from this manual that illustrate the specific installation to the vehicle owner.
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| Illustration 4 | g00720254 |
(1) Torque limit switch (2) "Ignore/Normal Brake/Clutch switch" (3) PTO On/Off switch (4) PTO switch ON lamp (5) PTO Set/RPM Increase/Decrease Switch (6) PTO Accelerator Assembly (7) PTO Switch On lamp (8) On/Off Switch for the "PTO Engine RPM Set Speed A" (9) On/Off Switch for the "PTO Engine RPM Set Speed B" | |