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Leeds & Northrup Company TABLE 11-OPTIONAL FEATURES FOR 10260 SERIES DRIVE MECHANISMS Feature suffix to Catalog No Rotary Position Sensor -A Weatherproof, Cat. 10261 to 10266, and 10269 -B1 Weatherproof, Cat. 10267 and 10268 -B2 Projecting scale, pointer, 3/4" shaft coupling -C1 Projecting scale, pointer, I " shaft coupling -C2 No main slidewire -D Auto-Manual Switch* -E Anti-backfire contact* -F Knurled output shaft 2 inches long; crank arm and swivel omitted*** -G1 No Acro-type switches -L One additional single-pole, double-throw, switch -L1 Two additional single-pole, double-throw, switches -1.2 Three additional single-pole, double-throw, switches -1.3 50-ohm main slidewire substituted for the 1000-ohm main slidewire -M 100-ohm main slidewire substituted for the 1000-ohm main slidewire -Ml 500-ohm main slidewire substituted for the 1000-ohm main slidewire -M2 Main slidewire omitted -N Limit switches (2 to 6) for multi-position operation (Directions 177243) P2 to P6 25-ohm shunt on auxiliary slidewire -R Oh mite rheostat, Model N -Sl 320* potentiometer. 5 watt -S2 High torque motor -T One auxiliary SO-ohm slidewire -Wl Two auxiliary SO-ohni slidewires -W2 Three auxiliary SO-ohm slidewires -W3 Multi-position operation with control relay (Directions 177244) -Y Linen tag 206 Aluminum tag 207 Stainless steel tag 208 Stocked valve: mounted and linked 301 to 1

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Leeds & Northrup Company

TABLE 11OPTIONAL FEATURES FOR 10260 SERIES DRIVE MECHANISMS

Featuresuffix to

Catalog No

Rotary Position SensorA

Weatherproof, Cat. 10261 to 10266, and 10269B1

Weatherproof, Cat. 10267 and 10268B2

Projecting scale, pointer, 3/4" shaft coupling-C1

Projecting scale, pointer, I " shaft couplingC2

No main slidewireD

AutoManual Switch*E

Antibackfire contact*F

Knurled output shaft 2 inches long; crank arm and swivel omitted***G1

No Acrotype switchesL

One additional singlepole, doublethrow, switchL1

Two additional singlepole, doublethrow, switches1.2

Three additional singlepole, doublethrow, switches1.3

50ohm main slidewire substituted for the 1000ohm main slidewireM

100ohm main slidewire substituted for the 1000ohm main slidewireMl

500ohm main slidewire substituted for the 1000ohm main slidewireM2

Main slidewire omittedN

Limit switches (2 to 6) for multiposition operation (Directions 177243)P2 to P6

25ohm shunt on auxiliary slidewireR

Oh mite rheostat, Model NSl

320* potentiometer. 5 wattS2

High torque motorT

One auxiliary SOohm slidewire-Wl

Two auxiliary SOohni slidewiresW2

Three auxiliary SOohm slidewiresW3

Multiposition operation with control relay (Directions 177244)Y

Linen tag206

Aluminum tag207

Stainless steel tag208

Stocked valve: mounted and linked301 to 308

* Permits local electrical operation of drive unit during installation, process startup, or anytime local manual process control is required. Applicable only to 10261,10262,10264,10266,10268, including suffix combination NL2. Not available with suffixes A, L3, PC3, POY, W2, W3, or combination S2Wl.

** The antibackfire contact is a stationary short across that end of the control slidewire (whose feedback signal determines the setting of the fuel control valve) that corresponds to the closed position of the fuel valve. Thus, if the fuel valve is closing, the antibackfire contact causes the drive mechanism to close the fuel valve completely before the burner backfirepoint is reached, thereby avoiding the danger.

*** Standard 2 " long shaft on 10263, 10265, and 10269. On all other units, where the G 1 suffix is not specified, the output shaft is 11/2" long. Refer to outline and dimension dwg. in this book.

Leeds & Northrup Company

The mechanism is shipped with three plugs mounted in the top cover as shown in Fig. 1. After the mechanism is installed, remove the plug in the uppermost position and mount the breather plug, which is furnished separately with the mechanism, in its place. This locates the breather plug above the level of the lubricant in the worm gear compartment. If the mechanism is mounted with its base down, remove any one of the three plugs, preferably the one in the middle. Note that the breather plug functions to prevent the formation of an atmospheric block in the lubricantfilled wormgear compartment.

All units with the S2 option: do not turn the handwheel beyond the 0 and 100 calibration limits indicated by the output shaft pointer. Otherwise the 320* potentiometer may be damaged.

3B. Linkage

(1) General Information

For many applications, the controlled device (final control element) will not provide linear regulation of the controlled quantity throughout its range of travel. A butterfly valve, damper, or similar device, will normally have the characteristic relationship between position and flow, as illustrated by the solid line in Fig. 2, where a valve is the controlled device.

Leeds & Northrup Company

A nonlinear toggle linkage can provide small increments of travel of the controlled device in the lower portion of its range and greater increments of travel in the upper portion of its range for equal increments of drive mechanism travel, as illustrated in Fig. 3. Thus, when toggle linkage is properly applied, it will tend to linearize the characteristic of the controlled device as illustrated by the dotted line in Fig. 2.

To install the linkage, it may be necessary to reposition the crank arm of the drive unit on the output shaft. To do this, loosen the clamp screw in the crank arm. After repositioning the crank arm, torque the bolt and nut to 4045 lb. ft.*, with antiseize compound applied to t he threads. After the linkage has been installed, position the pointer on the output shaft so that it indicates 0 to 100 on the scale as the crank arm moves between its limits of travel. Lubricate the swivels of the linkage.

The swivel assembly can be positioned at any point along the slot in the crank arm. Thus, the effective length of the crank arm can be adjusted to a maximum of 47/8 inches. To reposition the swivel assembly, simply loosen the swivel stud, slide the assembly to the desired position, and then retighten the stud; torque to 3035 lb. ft. Be certain to lubricate the swivel, stud, and all other linkage pins.

In many cases, the output shaft of the drive mechanism is arranged to rotate in a clockwise direction to close the valve (driven device). However, a check should be made to determine which direction the output shaft does rotate to close the valve (driven device) and then refer to the proper linkage diagram.

Fig. 3Characteristic curve for a nonlinear

toggle linkage operation of a valve

*75 lbft: on 10263, 10265, 10269, and all units with the 12" crank arm or 165 lbft for the 11261C6 crank arm.

Leeds & Northrup Company

(2) Linkage with Toggle Action

Fig. 4 illustrates linkage for four different operating positions of the controlled device, in this case a valve.

Fig. 4Four different positions ot controlled device sing linkage with toggle action.

Maximum toggle action is obtained when the drive mechanism crank arm and link rod are within 5o of dead center at the time when the con trolled device crank arm and link rod approach a 90 o angle. This is illustrated in Fig. 5 in which a valve is shown as the controlled device. It is to be noted that the drive mechanism crank arm moves through only 85o , since that is the limit of movement of the control slidewire. Reduced toggle effect is obtained when the drive mechanism crank arm link rod angle is increased through the range of 5 o to approximately 30 o .

The process should be tested to insure that the controlled device is effective through the entire range of drive mechanism travel, as illustrated in Fig. 5, and the link rod length adjusted accordingly. Note that with toggle action, it is particularly important that the limit switches be set properly to avoid damaging valve seats and possibly the drive unit itself, by exceeding the overhung load rating. A suggested test procedure is outlined in Section 3E.

Leeds & Northrup Company

(3) Linkage with Proportional Action

Proportional linkage is employed where the controlled device (characterized linear valve, speed control, etc.) will provide linear regulation of the controlled quantity.

Fig. 6 illustrates the linkage for two different positions of the controlled device, in this case a valve.

Leeds & Northrup Company

(4) Linkage for FuelAir Ratio Control

When a process includes control of fuel from temperature, and proportioning of air flow by means of a fuelair ratio controller, special attention must be given to arrangement of valve or damper linkages to provide proper functioning of the entire system.

Since fuel flow will be directly proportional to temperature change, the fuel control valve should be linearized either through the use of a characterized (linear) valve or by providing toggle action (as outlined in Section 3B2) in the fuel control valve linkage.

Conversely, since the air control valve drive unit will respond to a linear relation between fuel flow differential and air flow differential (thus to fuel flow squared) the air' control valve must be moved faster in the lower end of its range and slower in the upper end of its range to match the speed of response of the oil valve control.

An inverse toggle action, illustrated in Fig. 7, applied to the air control valve, will provide the desired response characteristic.

Leeds & Northrup Company

For those installations where air flow is controlled from temperature and fuel is controlled by fuelair ratio, the air control valve should be linearized, and the fuel ontrol valve will require inverse toggle linkage.

3C. Limit Switches

The limit switch cams, Fig. 8, are adjusted at the factory to operate at the extremes of the indicating scale (85o travel of the operating crank) and normally need not be changed in the field.

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