Control-lever stops
On every governor there are stops for the minimum and maximum control-lever deflection. If, for example, the driver fully depresses the accelerator, the control lever is brought into contact with an adjustable stop screw. Adjusting the screw alters the control-lever deflection, i.e. the
injected fuel quantity, on a minimum/ maximum-speed governor
the maximum speed on a variable-speed governor.
The stop screw is factory-adjusted and sealed; tampering with it voids the manufacturer’s warranty.
The other stop is normally used to adjust the idle speed. This stop may be sprung or rigid.
Rigid stop
With a rigid stop (Figure 1) the fuel-injection equipment must incorporate a separate device for stopping the engine.
Sprung stop
If a sprung stop is used (Figures 2 and 3) the stop setting is reached by pressing the lever past the stop position against the force of the spring.
If necessary, the minimum stop can be set to “shutoff ”, but in this case there must be a low-idle stop elsewhere on the engine.
Stops for intermediate fuel volumes or engine speeds
Stops for intermediate control lever settings can be fitted as an option.
Depending on governor type, either a “reduced-delivery stop” for setting a lower full-load delivery quantity, or an “intermedi- ate-speed stop” for setting an engine speed below nominal speed can be used (Figure 4).
84 Governors and control systems for in-line fuel-injection pumps Calibration devices
Fig. 1
1 Stop for idle speed (or shutoff) 2 Stop for full-load
volume on minimum/ maximum-speed governor or for nominal speed on variable-speed governor Fig. 2 1 Lever 2 Stop lever 3 Control-lever shaft 4 Clamping screw 1 2
Rigid control-lever stops
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U M K0549-1Y 1 2 3 4Stops for reduced volume on minimum / maximum-speed governor or for intermediate speeds on variable-speed governor (external view)
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U M K055 1-1YControl-rod stops
Apart from the stops for idle speed/shutoff, full-load volume/maximum speed (present on every governor for limiting control-lever movement) a special stop is required to limit control rack travel at full load or when starting from cold.
There are also full-load stops for performing specific compensating functions. Control-rod stopsmaybefittedonthefuel-injectionpump or on the governor. A selection of the possible variations is described below in more detail.
Rigid start-quantity stop
The rigid start-quantity stop is used primarily on Type RQ governors with low idle-speed settings (Figure 5). When the engine is run- ning, the excess fuel for starting is backed off by the governor so that it does not have an adverse effect (emission of smoke).
Governors and control systems for in-line fuel-injection pumps Calibration devices 85
Fig. 4 a Locked b Released 1 Lever 2 Housing 3 Spring 4 Switching shaft 5 Stud 6 Control-lever shaft Fig. 5
1 Excess starting fuel adjusting screw 2 Stop pin 3 Stop lug 4 Start-quantity limitation 5 Link fork Fig. 3 a Shutoff b Idle speed 1 Spring 2 Threaded sleeve 3 Pin 4 Stop lever 5 Screw cap 6 Locking nut 7 Fixing bracket 8 Control-lever shaft 9 Clamping screw 1 3 4 5 2 6 a b
Stops for reduced fuel volumes or intermediate engine speeds 4
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U M K0552-1Y 1 2 3 4 5Rigid control-rod stop for limiting start quantity on Type RQ governor 5
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U M K0553-1Y 1 2 3 4 a b 9 8 7 6 5Sprung control-lever stop (Type RQ and RQV governors)
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Sprung start-quantity stop for Type RQ governor
When the engine is started (accelerator fully depressed), the stop pin is moved against the resistance of the spring to the set start-quantity position. The spring in the stop acts against the idle-speed spring and thus initiates early returnof thecontrolrackfromthestart-quantity position(Figure6).Thatmeansthatif theengine is accelerated rapidly from idle speed, partial application of the start quantity is prevented.
Automatic full-load stop
When the engine is not running, the governor springs in the flyweights act via the sliding bolt (Figure 8, Item 13) to overcome the rocker spring (12). The rocker (9) pushes the stop strap (8) with the full-load stop (7) down- wards (position shown in gray). If the accel- erator is fully depressed when the engine is started, the control rack (6) can be moved to the start-quantity position.
After the engine has started, the sliding bolt is drawn back from the rocker (arrow)
by the action of the flyweights. For the same reason, the control rack moves back from the start-quantity position to a lower quantity setting. Consequently, the rocker spring pivots the rocker so that its long arm moves back upwards (position shown in blue). The full-load stop once again pre- vents the control rack moving past the full- load position by catching against the lug on the link fork (4).
Stop with external torque-control mechanism for Type RQV governor
This external stop provides the facility for adjusting the full-load control-rod position and the torque-control settings (starting point, characteristic and travel). Torque control is effected by the interaction between the gov- ernor drag spring and torque-control spring (Figure 7) and requires that the springs are precisely matched to one another.
If there is also a tension spring for enabling the start quantity, the rocker (i.e. speed-de- pendent enabling) is omitted (Figure 9).
86 Governors and control systems for in-line fuel-injection pumps Calibration devices
Fig. 6 1 Spring 2 Governor cover 3 Governor housing 4 Control-rod link fork
a Start-quantity stop travel
Fig. 7
Torque-control spring overcomes drag spring 1 Torque-control spring 2 Control rack 3 Drag spring a Torque-control travel 1 2 3 4 a
Sprung control-rod stop for limiting start quantity on Type RQ governor 6
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U M K0554-1Y 1 a 2 3 Full power ShutoffControl-rod stop with torque-control mechanism for Type RQV governor
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Governors and control systems for in-line fuel-injection pumps Calibration devices 87
Fig. 9
a Start-quantity position
b Full-load setting with torque control 1 Locking pin 2 Governor cover 3 Link fork 4 Variable-fulcrum lever 5 Start-quantity lever 6 Lever compression spring 7 Threaded sleeve 8 Torque-control spring 9 Adjusting screw x Torque-control travel y Start-quantity stop travel Fig. 8
Position shown in gray: start quantity enabled Position shown in blue: full-load quantity setting
11 Full-load quantity adjuster 12 Governor cover 13 Governor housing 14 Stop lug 15 Link fork 16 Control rack 17 Full-load stop 18 Stop strap 19 Rocker 10 Variable-fulcrum lever 11 Control-lever shaft 12 Rocker spring 13 Sliding bolt a Start-quantity stop travel 1 2 3 4 y b a 5 6 7 x 8 9
Control-rod stop for Type RQV governor with lever for excess starting fuel and torque-control mechanism
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U M K055 7 -1Y 1 2 3 5 6 8 9 10 11 12 13 4 7 aAutomatic full-load control-rod stop for Type RQV governor
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Stop with internal torque-control mechanism for Type RQV governor
The control-rod stop with internal torque- control mechanism (Figure 12) for Type RQV governors protrudes only approximately 25% of the length of the stop with external torque- control mechanism. Designed for situations where space is limited, this stop allows adjust- ment of the point at which torque control starts and the torque-control travel, but not the torque-control rate.
Pump-mounted stops
The full-load volume is generally adjusted on the governor. However, there are also rigid and sprung control-rod stops for mounting on the drive input side of the fuel-injection pump. They normally set the maximum permissible start quantity, and in a few cases the full-load volume as well.
Rigid version
A rigid stop set to the excess fuel for starting as shown in Figure 10 can be used in place of the governor-mounted stop shown in Figure 5. A rigid stop set to the full-load position will, by definition, not permit excess fuel for starting. Sprung version
A pump-mounted sprung control-rod stop as shown in Figure 11 can be used in place of the governor-mounted stop shown in Figure 6; its function is identical.
88 Governors and control systems for in-line fuel-injection pumps Calibration devices
Fig. 12
1 Link with torque control mechanism 2 Adjusting screw for
torque-control starting point 3 Torque-control
spring
4 Adjusting screw for torque-control travel 5 Full-load stop 6 Control rack a Torque-control travel Fig. 11 a Full-load position b Start position 1 Control rack 2 Stop sleeve 3 Spring 4 Locking nut 5 Stop 6 Adjusting sleeve Fig. 10 1 Control rack 2 Screw cap 3 Adjusting screw 4 Stop surface 1 2 3 4
Rigid control-rod stop
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U M K0660-1Y b a 1 2 3 4 5 6Sprung control-rod stop
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U M K066 1-1Y 1 2 3 4 5 a 6Type RQV governor with internal torque-control mechanism
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Type LDA manifold-pressure compensator
Usage
On turbocharged engines, the full-load volume is set on the basis of the turbocharger pressure. However, the turbocharger pressure is lower at lower engine speeds and the mass of the cylinder charge therefore smaller. Conse- quently, the full-load volume must be adjusted in proportion to the smaller amount of air. The Type LDA manifold-pressure compen- sator reduces the full-load delivery quantity at lower engine speeds from a specific (selec- table) turbocharger pressure onwards. There are versions of the manifold-pressure com- pensator for fitting on the fuel-injection pump as well as on the governor (top or rear). The version described below is intended for fitting on the Type RSV governor (Figures 13, 14 and 15).
Design and method of operation
The design of all such control-rod stops is essentially the same. In between the com- pensator housing, which screws onto the top of the governor, and its cover there is a di- aphragm which forms an airtight seal (Fig- ure 13, Item 3). In the compensator cover, there is a connection via which the manifold (turbocharger) pressure pLacts on the di-
aphragm. A compression spring (4) acts on the diaphragm in the opposite direction from below. The other end of the compres- sion spring is seated on a guide sleeve (5)
Governors and control systems for in-line fuel-injection pumps Calibration devices 89
Fig. 13 11 Grub screw 12 Diaphragm disc 13 Diaphragm 14 Spring 15 Guide bushing 16 Pin 17 Setting shaft 18 Bell crank 19 Rigid link 10 Control rack 11 Governor housing 12 Starting spring 13 Governor cover 14 Variable-fulcrum lever pL Manifold pressure Fig. 14 a Normal operation setting b Position of link
relative to bell crank for starting 1 Rigid link 2 Setting shaft 3 Bell crank 4 5 1 2 3 7 8 9 11 10 pL 12 13 14 6
Type LDA manifold-pressure compensator for Type RSV governor 13
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U M K0560-1Y a b 1 2 3Type LDA manifold-pressure compensator for Type RSV governor
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which screws into the governor housing. The initial tension of the spring can thus be var- ied within certain limits.
The diaphragm is attached to a pin (6) that has a transverse slot cut into its lower end. A stud on the end of the bell crank (7) locates in that slot. When the manifold-pressure compensator is fitted on the governor, mi- nor adjustments can be made by means of the grub screw (1). When the charge-air pressure is acting on the diaphragm, the pin is moved against the force of the compres- sion spring. The maximum pin travel occurs when the charge-air pressure is at its highest. The pin acts via the bell crank, which pivots around a bell crank mounted inside the gov- ernor housing, and the rigid link, and thus ultimately on the control rack (10) of the fuel-injection pump. When the charge-air pressure drops, the control rack is moved to- wards the stop setting.
A version of the manifold-pressure compen- sator for Type RQV governors is shown in Figure 16.
In order that the control rack can be set to the start-quantity position for starting the engine, the bell crank can be disengaged from contact with the rigid link by lateral move- ment of the setting shaft (Figure 14). This can be effected manually either by means of a cable-operated mechanism or a rod linkage;
there are also governor designs where the set- ting shaft is operated by an electromagnet that is only energized during the starting sequence. A thermostatic switch can cut off the power supply to the solenoid if the start quantity is not required due to the temperature of the engine.
The Type HSV hydraulic start-quantity locking device is another variation on the same theme that is operated by the engine- oil pressure. In this case, the oil pressure generated when the engine is started locks the excess fuel for starting. The hydraulic start-quantity locking device is screwed onto the side of the governor housing.
90 Governors and control systems for in-line fuel-injection pumps Calibration devices
Fig. 16 Adjusters for: 1 Suction quantity 2 Press-charge fuel-delivery quantity 3 Cutin point Engine speed 1,000
Control rod travel
1,500 2,500
Without MPC
With MPC mm
rpm
Effect of manifold-pressure compensator on maximum control-rod travel
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U M K056 1-1E 1 2 3Type LDA manifold-pressure compensator for Type RQV governor
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Type ADA altitude-pressure compensator
Usage
Engines that are used at widely varying alti- tudes require adjustment of the injected fuel quantity to take account of the reduced mass of the cylinder charge upwards of a specific altitude.
The Type ADA altitude-pressure compen- sator (Figures 17 and 18) reduces the injected fuel quantity in response to increasing altitude (diminishing atmospheric pressure). On Type RQ(V) and RSF governors is fitted on the governor cover.
Design and method of operation
On the Type RQV governor, the altitude-pres- sure compensator consists of a barometric capsule (3) that is fitted vertically inside an outer housing and can be adjusted to a spe- cific altitude setting by means of an adjusting screw (1) and an opposing spring-loaded pin (5). As the altitude increases, the barometric capsule expands.
The spring-loaded pin resting against the underside of the barometric capsule and the fork (4) screwed onto the end of the pin transmit the expansion and contraction of the barometric capsule to the pivoted cam disc (8). The cam disc acts on the pin con- nected to the stop strap. The cam disc pivots downwards. The pin attached to the stop strap moves the control rack towards the stop set- ting and the fuel delivery quantity is reduced. If the barometric capsule contracts again due to a reduction altitude, the delivery quantity increases again. The cam disc can be ad- justed in the horizontal plane by means of a screw in order to set the full-load volume.
The arrangement and design in the case of the Type RSF governor are similar. In this case, changes in altitude are transmitted to the fuel-injection pump control rack by a spring-loaded pin and a series of connected levers. A similar design is also used on the Type RQ governor.
Governors and control systems for in-line fuel-injection pumps Calibration devices 91
Fig. 18 1 Adjusting screw 2 Cap 3 Barometric capsules 4 Clevis 5 Spring-loaded pin 6 Connection to outside (for detecting atmospheric pressure) 7 Compensating link 8 Cam disc mm Altitude over N. N.
Control rod travel
0 1,000 2,000 3,000 4,000 13
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Adjustment by APC
Adjustment of control-rod travel by Type ADA altitude-pressure compensator 17
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U M K0563-1E 1 2 3 8 6 7 4 5Type ADA altitude-pressure compensator
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Type ALDA absolute manifold-pressure compensator
Usage
The charge-air pressure of the turbocharged engine is measured relative to the ambient atmospheric pressure, the effect of which is felt most strongly when there are significant changes in altitude. If atmospheric pressure and manifold pressure are added, the absolute pressure is obtained.
Design and method of operation
The absolute manifold-pressure compensator on the Type RSF governor also has barometric capsules that can be adjusted for different al- titudes and which are subjected to the absolute pressure via a connection to the engine’s in- take manifold (Figure 19, Item 1).
The barometric capsules respond to changes in pressure by expanding or contracting, thereby adjusting the injected fuel quantity by acting on a system of levers connected to the control rack.
Type PLA pneumatic idle-speed increase
Usage
The fuel volume required by a diesel engine when idling diminishes as engine tempera- ture increases.
The temperature-dependent idle speed in- crease on the Type RSF governor (Figure 20) increases the engine’s idle speed when it is cold, thus helping the engine to warm up more quickly. It also prevents the engine from dying if auxiliary equipment such as power steering, air conditioning, etc. cuts in while the engine is still cold. Once the engine has reached a certain temperature, it ceases to operate.
Design and method of operation
A temperature-dependent vacuum acts on the diaphragm (3) in the vacuum unit. The di- aphragm moves a sliding bolt (2) which varies the tension on the idle-speed spring (1). This causes the governor linkage to move the con- trol rack to a higher fuel-quantity setting.
92 Governors and control systems for in-line fuel-injection pumps Calibration devices
Fig. 19 1 Connection to engine intake manifold (absolute pressure detection) 2 Adjusting screw 3 Pressure capsule 4Barometric capsules 5 Compensating linkage 6 Plate cam Fig. 20 1 Idle-speed spring 2 Sliding bolt 3 Diaphragm 4Vacuum connection 5 Vacuum unit 6 Compression spring 2 1 3 4 5 6
Type ALDA absolute manifold-pressure compensator
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U M K0630-1Y 1 2 3 4 6 5Type PLA pneumatic idle-speed increase
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U M K063 1-1YType ELR electronic idle-speed control system
Usage
Instead of normal pneumatic idle-speed in- crease, the Type RSF can be combined with an electronic idle-speed control system for more demanding applications.
Design and method of operation
The electronic idle-speed control system consists of
an electronic control unit, and an actuator solenoid.
The electronic control unit adjusts the idle speed by means of the actuator solenoid in response to changes in temperature and en- gine-load conditions. As shown in Figure 21, the actuator solenoid is mounted on the Type RSF governor cover in such a way that the energized solenoid armature can aug- ment the force of the idle-speed spring and thus increase the idle speed.
Type ARD surge damping
Usage
Pulsations caused by sudden load changes can be largely eliminated by the use of surge damping on the Type RSF governor.
Design and method of operation
Surge damping consists of an electronic control unit, an engine speed sensor and an actuator solenoid.
The electronic control unit reads and ana- lyzes the signals from the engine-speed sensor. In order to prevent vehicle judder caused by bucking oscillations, it operates the actuator solenoid (Figure 21, Item 2) of the Type RSF governor in such a way that it moves the lower anchor point of the variable-fulcrum lever to a less extended position in response to the oscillations. As a result, the injected fuel quan- tity is reduced accordingly, thereby counter- acting the bucking oscillations.
Governors and control systems for in-line fuel-injection pumps Calibration devices 93
Fig. 21
1 Actuator solenoid for electronic idle-speed control 2 Actuator solenoid
for active surge damping
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Type RSF governor with electronic idle-speed control and active surge damping
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Type TAS temperature-compensating start-quantity stop
Usage
On many engines, a greater start quantity is only required at low ambient temperatures when the engine is also cold. For environmen- tal safety reasons, unnecessary injection of ex- cess fuel for starting should be avoided. The temperature-compensating start-quantity stop ensures that the quantity delivered when start- ing does not exceed the required amount as specified by the engine manufacturer. This de- vice is available for virtually all governor types.
Design and method of operation
With the aid of an expansion element
(Figure 25) that responds to ambient tem- perature or a temperature-controlled elec- tromagnet (Figure 26), the start quantity is limited when hot-starting the engine by limiting the control rack travel according to ambient temperature.
Depending on the fitting constraints on the fuel-injection pump and the type of gov- ernor, the following types of expansion ele- ment/ electromagnet are used:
1. If there is sufficient space on the drive in-