US 3467260 A
Description (OCR text may contain errors)
Sept. 16, 1969 J. R. THOMPSON 3,467,250
SNORKEL-EQUIPPED LOADING BOOM WITH SAFEGUARD AGAINST DESTRUCTIVE BENDING OF SNORKEL Filed July :51, 1967 2 Sheets-Sheet 1 FIG IN VENTOR. JAMES RUSSELL THOMPSON ATTORNEYS Sept. 16, 1969 J. R. THOMPSON SNORKEL-EQUIPPED LOADING BOOM WITH SAFEGUARD AGAINST DESTRUGTIVE BENDING 0F SNORKEL 2 Sheets-Sheet 2 Filed July 31, 1967 JAMES RUSSELL THOMPSON INVENTOR.
ATTORNEYS United States Patent 3,467,260 SNORKEL-EQUIPPED LOADING BOOM WITH SAFEGUARD AGAINST DE- STRUCTIVE BENDING OF SNORKEL James R. Thompson, Seattle, Wash., assignor to Washington Iron Works, Seattle, Wash., a corporation of Washington Filed July 31, 1967, Ser. No. 657,369 Int. Cl. B66c 1/32, 23/06, 23/66 US. Cl. 2127 7 Claims ABSTRACT OF THE DISCLOSURE The invention relates to an overload protector for the snorkel of a snorkel-equipped log-loading boom, and aims to provide a mechanism of a simple and inexpensive construction which will effectively protect the snorkel, which has the log grapple suspended from its outer end, against liability of being subjected to destructively heavy loads such as that of a log while the snorkel is in an extended position.
With this and other objects and advantages in view and which will appear and be understood in the course of the following description and claims, the invention consists in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.
In the accompanying drawings:
FIGURE 1 is a side elevational view illustrating structure embodying the preferred teachings of the present invention in its working environment with a snorkelequipped loading boom, the boom being shown in phantOIIl.
FIG. 2 is a fragmentary enlarged-scale top plan view showing the outer end of the snorkel.
FIG. 3 is a fragmentary side elevational view of the snorkel.
FIGS. 4 and 5 are transverse vertical sectional views drawn to an enlarged scale on lines 44 and 55, respectively, of FIG. 3; and
FIG. 6 is an enlarged-scale view similar to FIG. 2 with parts broken away and shown in section with the cable deleted.
Referring to said drawings, the numeral 10 denotes a foundation on which there is mounted a turntable 11. The turntable gives pivot support to the inner end of a vertically swingable loading boom 12 and carries a plurality of spooling drums together with an engine for powering the turntable, the spooling drums, an air compressor, and a hydraulic pump. Compressed air controls the drums and a reversible valve for a hydraulic motor which operates a snorkel appendage for the boom. There are three drums related to the loading operation. The boom is raised and lowered by operation of a drum 13. Drum 14 handles a load line 15 for a tong-grapple 16, and drum 17 handles a holding line 18 for said grapple. The load line runs directly to the grapple from sheaves 20 located at the outer end of the boom. The holding line 18 passes over a sheave 21 which is hung by a line 22 from the outer end of the snorkel.
Functionally considered, the snorkel of the present invention is like or similar to that illustrated and described in US. Patent No. 2,878,946, and this is to say that an outer leg 23 of the boom has a telescoping assembly supported thereon. This assembly comprises a reach section 24 received for endwise motion within a mount section 25 with the reach movement being in an outward direction relative to the boom along an axis generally paralleling said outer leg of the boom.
Rollers 26 and 27, the former carried by the reach member at its inner end and tracking against the top wall of the mount section and the latter carried by the mount section and tracking upon the underside of the reach section, guide the reach section in its endwise motion. The reach section 24 is powered in its extension and retraction movements by a double-acting hydraulic jack. The cylinder 28 of the jack has its rear end pivoted at 29 to the mount section 25. The piston rod 30 of the jack is pivoted at 31 to lugs 32 made integral with the reach section. Rollers 33 support the cylinder 28 at its outer end, riding upon the bottom wall of the reach section.
A yoke-shaped bracket 34 is bolted or otherwise rigidly secured to the reach section at its extreme outer end. A shaft 35 extends transversely between the yoke arms with its ends journaled between the base and cap components of split blocks. Journaled on the shaft is a winding drum 37, and keyed to the shaft and acting in complement to normally hold the drum against rotation are a pressure plate and a thrust plate 41. The pressure plate carries a friction surfacing 42 which bears against an end face of the drum, and the thrust plate acts through Belleville springs 43 to adjustably tension the pressure plate, the adjustment being afforded by a nut 44 working on a threaded portion of the shaft. When the nut is turned in a right-hand, or tension-increasing, direction the shaft and the two plates keyed thereto are held against rotation by a dog 45 which catches behind one of a set of ratchet teeth 46 formed in the perimeter of the pressure plate. A removable pin 47 locks the dog in this position. The aforementioned sheave 21 is made a part of a fitting which includes a track sheave 48, and the latter is caught in a loop of the line 22. One end of the looped line is anchored at 50 to the outer end of the snorkel. The other end is wound on the drum 37, with the direction of wind such that a ratcheting action of the friction-coupled drum and plate assembly 37-40-41 takes in on the line.
The setting given to the thrust plate by a turning of the adjusting nut 44 is that which will give to the friction couple a resistance loading sufiicient to counter no more than a downward pull of given intensity to which the sheave 21 may be subjected, from the holding line 22, when the snorkel occupies its extended position. This given pull represents a predetermined limit of terminal loading which the extended snorkel can safely carry without liability of becoming damaged.
It will be understood that the operator, having extended the snorkel to bring the tong grapple into proximity of a log which is to be heeled against the boom incident to loading the log upon the bed of a truck, retracts the snorkel before pulling the log toward the boom. A snorkel-damaging overload can of course occur through negligence of the operator should he fail to retract the snorkel before taking in on the load and hold-- ing lines. More frequently, however, the cause lies in the fact that when the grapple is applied to a log the weight of the grapple causes the log to roll so that there is passed into the holding line 22 a heavy loading force, which is nnassociated with any operation of the spooling drums, before the operator has been enabled to retract the snorkel. The automatic slippage afforded by the adjustable friction couple of the present invention protects against damage to the snorkel regardless of the overloading cause.
It is believed that the invention will have been clearly understood from the foregoing detailed description of my now-preferred illustrated embodiment. Changes in the details of construction may be'resorted to without departing from the spirit of the invention.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. In combination with a loading machine of the character described having a hinged loading boom with cableways at the outer end and extensible in point of its range by an extensible snorkel which is carried upon the boom in non-hinging relationship and has a cable-way at the outer end, providing power-driven means on which a loading cable and a holding cable are spooled, and having a log-engaging means to which the outer ends of 'both cables are secured, the loading cable running from the spooling means through a cable-way of the boom and then directly to the log-engaging means, the holding cable running from the spooling means through a cable-way of the boom and then through the cable-way of the snorkel before connecting with the log-engaging means, said snorkel when extended being structurally incapable of supporting loads in the holding cable typically borne by the boom through the loading cable: a mechanism acting automatically to relieve tension in the holding cable sufficient to preclude destructive bending of the snorkel in the circumstance of an engaged log passing through said cable into the outer end of the snorkel while the snorkel is in an extended condition a load in excess of a predetermined safe limit.
2. The combination of claim 1 in which the cable-way of the snorkel is provided in a block suspended from the outer end of the snorkel by a cable having its other end spooled upon a winding drum, the tension-relieving mechanism comprising a friction plate located co-axial to the drum and exerting upon an end face of the drum an endwise pressure of predetermined intensity, means being provided holding the friction plate against turning motion in the unwinding direction of the drum.
3. The combination of claim 2 in which the endwise pressure exerted by the friction plate admits of being pre-set to selected intensities.
4. The combination of claim 2 in which said holding means comprises a dog functional to the teeth of a ratchet wheel which is secured to the friction plate.
5. The combination of claim 2 in which said holding means comprises a dog functional to the teeth of a ratchet wheel which is secured to the friction plate, a releasable means being provided for locking the dog in a toothcatching position.
6. The combination of claim 2 in which the drum and tension-relieving mechanism are mounted upon the outer end of the snorkel.
7. The combination of claim 1 in which the automatically acting mechanism comprises means responsive to tension in the holding cable above a predetermined limit applied to the drum.
References Cited UNITED STATES PATENTS 2,704,191 3/1955 Schley. 2,917,278 12/1959 Arnold 254150 3,011,651 12/1961 McIntyre 2l2-7 3,051,447 8/1962 Ahlbin 254-187 3,301,533 1/1967 Pfaff 254187 EVON C. BLUNK, Primary Examiner H. C. HORNSBY, Assistant Examiner US. Cl. X.R.