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HYDRAULIC GATES (Continued)
B. The capacity of the hoist required is
H = 0.35 AP + W.
C. The largest gate of this type for which standard drawings are available is 6.4 feet by 8 feet 0 inches, and the smallest 2 feet 0 inches by 2 feet 0 inches. Typical examples of a cast-iron gate and a hand-operated hoist are shown on Drawings Nos. 100-C-85 and 100-C-68, respectively. A complete list of sizes and drawing numbers can be obtained from the Drawing and Data Files, Denver. Standard gates are generally available in the open market as stock items from manufacturers of irrigation equipment.
Screw-lift turnout gates are for use along canals and laterals to control the
A. A complete list of sizes and drawing numbers for screw-lift gates can be
The roller gate or rolling wier, although a European development, has been used extensively in this country over a period of more than 35 years. One of the earliest American installations was for the diversion dam across the Colorado River near Grand Junction, Colorado, which was built by the Bureau of Reclamation. These gates have given satisfactory service in continuous operation since 1915. Recent installations consisting of four gates for the All-American Canal headworks on the lower Colorado River (1937) and two ates for the Roza Diversion Dam, Roza Division, Yakima Project, Washington 1939) were installed by the Bureau of Reclamation.
A. Roller gates are more generally used on extremely low head dams and in
Components B. The roller gate consists of a horizontal, hollow, steel-plate cylinder
of the which extends into a vertical or steeply inclined recess in each end pier.
Gate An apron, extending along the length of the cylinder, effects a seal with the bottom of the waterway when the gate is at the lowest point of its travel. In case the gate is not designed for passing ice or trash over the top, it is generally provided with a flash weir, similar to the apron, but extending upward when the gate is in the closed position. The purpose of the flash weir is to prevent overtopping of the gate by waves and to provide freeboard above the highest longitudinal element of the cylindrical shell.
Around each end of the cylinder is a rim consisting of a gear and a smooth
Method C. Watertightness along the Sill, in case of a nonsubmergible gate, is usually
of Sealing effected by means of an oak beam bolted to the apron and resting on an adjustable I-beam sill. To obtain watertightness along the sides, the gate is provided with flexible shields attached to the upstream face of the gate and extending from the bottom seal on the apron to the top of the flash wier. To the upstream edge of each shield is bolted an oak or rubber sealing strip. The sealing strips travel on and bear against Steel or machined cast-iron armature plates set in the piers. In the case of . submergible gates, a well is provided in the crest of the dam. When the gate is submerged to allow ice and trash to pass, the apron extends into the well and a special rubber seal usually maintains contact between the apron and the upstream wall of the well.
Hoisting D. The rotation of the gate to effect raising is accomplished by means of a sprocket chain around the end of the cylinder and attached to a chain anchor at one end of the gate and actuated by a motor-driven sprocket-chain hoist. The hoist is usually located in a hoist house on top of one of the end piers. In the case of several gates in a group, two hoists are usually placed together in one hoist house. Only alternate piers will thus have hoist houses. A locking link is usually provided, which may be latched to the gate in its fully raised position, thus securely holding the gate and permitting the sprocket chain to be removed.
Roller gates have been installed in this country and in Europe that vary
The 110-foou roller gates which were installed at Roza Diversion Dam
1.29E HYDRAULIC GATES (Continued) MISCELLANEOUS GATES (Continued)
is especially significant for the larger sized roller gates. The gears and
E. The hoist frame, which supports the gear bearings, is composed of two Hoist Frame parallel plate-steel girders tied together at the ends by means of angle web stiffeners. One end of the hoist frame rests on fixed base plates. The other rests on Sliding plates to accommodate temperature variations in the main girders. Care should be exercised in the design of the hoist girders so that, when the maximum hoist load is applied, the resultant deflections will be the same in each girder. This produces uniform tooth pressures between the pinion and gear for the full face width, and is especially necessary when Straight-toothed spur gears are used. The maximum tensile and compressive stresses should not exceed 75 percent of minimum yield point of the material used at breakdown of the motor.
The hoist chain should be of the roller type. Due to high bearing pressures
.30 Power-operated gate hoists are usually used for operating low-head slide POWER
- gates. They are built in sizes ranging from 7,000- to 40,000-pound capacity. OPERATED A typical gate hoist consists of a cast-iron pedestal on which is mounted a GATE commercial vertical gear-motor. The motor, through gearing, drives an HOISTS Acme-threaded, bronze stem nut which rotates on and raises a threaded steel gate stem. The control unit consists of a rotating-type limit switch to limit the upper and lower gate travel, and a pointer to indicate the gate opening. A Selsyn transmitter for remote position indication may be furnished if required.
A. The thrust load on the stem is carried on ball thrust bearings. The Design pedestal covers, with the exception of those for the smallest hoist, are Considerations made of cast steel and are designed to take any upward thrust due to seating the gate with the limit switch inoperative. The hoist is so designed that the maximum stress under the breakdown torque of the motor will not exceed 80 percent of the yield point of the materials used. The unsupported length of stem is limited to an 1/r of 200, based on the root diameter of the threaded portion or on the outside diameter of the unthreaded portion of the Stem.
B. A complete list of hoist capacities and drawing numbers can be obtained Reference from the Drawing and Date Files, Denver. Examples of power-operated Drawings gate hoists and the control unit are shown on the following drawings:
GATE HOISTS (Continued)
RADIAL .31 Radial gates are normally hoisted by a two-drum, manually or power-operated
Manually Operated Gate Hoists
wire-rope hoist. The hoisting ropes are usually connected to lugs near the bottom of the upstream face of the gate. In the case of top seal gates the connection is made at the top of the gate.
A. Manually operated hoists are used for capacities up to and including 5,000 pounds. Such a hoist consists of a 50 to 1 commercial worm-gear reducer with a 3 to 1 helical gear attachment, and the drums are directly connected to the worm-gear shaft. Ungrooved rope drums having a minimum diameter of 18 times the diameter of the rope are used.
B. Power-operated hoists are used for capacities greater than 5,000 pounds.
C. The 3,000-pound and 5,000-pound-capacity manually operated hoists and the 5,000-pound power-operated hoists are of two types. One type has the drive unit centrally located, and the other has the drive unit located at one end of the hoist which allows a narrower concrete deck to be used.
Hoisting speeds for power-operated hoists vary from 1-1/3 to 2-1/4 feet
Ball or roller self-alining bearings or ball-bearing self-alining pillow blocks are used for all hoists except those operated manually. Plain, babbitted, flat box bearings are used on the manually operated hoists. Flexible couplings are of the all-metallic, dustproof, and fully enclosed
type. D. A complete list of hoist capacities and drawing numbers can be obtained
from the Drawing and Data Files, Denver. Examples of standard radial gate hoists are shown on the following drawings:
1.32 GATE HOISTS (Continued) 3,000-pound, Hand-operated Hoist Reference (Figure 43) - - 40-D-4329 Drawings (Cont. 5,000-pound, Hand-operated Hoist (Figure 56) 40-D-4078 5,000-pound, Power-operated Hoist (Figure àij - 40-D-3988 10,000-pound, Power-operated Hoist (Figure 52) 40-D-4684 60,000-pound, Power-operated Hoist (Figure 53) 40-D-4646 Chain-and-sprocket hoists are used to raise and lower large gates which MECHANICAL regulate the discharge of water over spillways and are operated only at HOISTS FOR infrequent intervals. A complete assembly drawing of a 50- by 50-foot FDXED-WHEEL gate hoist of this type is shown in Figure 54. The hoists are powered with OR electric motors. Each hoist, as shown in Figure 54, consists of a motor- ROLLERdriven reduction unit having two output shafts each of which is connected to MOUNTED a gear-reduction hoist unit. Each hoist unit is equipped with a drive sprocket, GATES an idler sprocket, and a sprocket chain. One end of each sprocket chain is attached to the regulating gate and the other end of the chain is attached to a counterweight. A. The hoisting speed depends largely upon the operating requirements of Hoist the spillway. In cases where flood control is the primary purpose of the Operating gates, faster hoisting speeds are required, but where regulation only is Speeds to be considered slower speeds may be used. The size of the gate also influences the hoist speed and in cases where large gates of the 50- by 50-foot class are to be moved, speeds ranging from 0.3 to 1.0 foot per minute are most frequently used. Smaller gates of the 30- by 30-foot class are hoisted at speeds ranging from 0.5 to 1.5 feet per minute. B. For stresses in the hoist chain links, refer to Technical Memorandum Design No. 558. The maximum stress in the chain link should not exceed 75 Stresses percent of the yield point of the material used when the pull-out torque of the motor occurs. Particular attention should be given to providing adequate pin clearances in the links. C. Typical designs of mechanical hoists are illustrated in the following Reference drawings: Drawings 50- by 50-foot Regulating Gate Hoist, Complete Assembly--Keswick Dam 214-D-8870 Main Hoist and Spur Gear Assembly 214-D-8871 The hydraulic type of hoist is usually placed on the upstream face of a dam, HYDRAULIC with the top of the hoist just below the road or walkway, and is used for HOISTS FOR raising or lowering the fixed-wheel or roller-mounted gate that closes the FIXED-WHEEL upstream end of a penstock or outlet conduit. A hydraulic hoist consists of a OR vertical cylinder, piston, and stem, with the stem passing through a packing in ROLLERthe lower cylinder head. The upper cylinder head contains latches that hold MOUNTED the piston and stem in the raised position without maintaining oil pressure GATES
below the piston. The piston stem is connected to the gate stem for low-head installations, or has intermediate sections of stem between the piston and gate for high-head installations. The entire assembly is supported on a bracket resting on the concrete. An assembly drawing of a hoist of this type is shown
in Figure 53.