US2368268A - Crane and the like load lifting apparatus - Google Patents

Description

Jan. 30, 1945. P. SPIEGEL CRANE AND THE LIKE LOAD LIFTING APPARATUS 2 Sheets-Sheet l N in 00 mm mw m R O T N E V NL E 6 F Ur S P. M H P TTORNEY- 2 Sheets- -Sheet 2 lNVENTOR PHILIP SPIEGEL P SPIEGEL Filed Jan. 4, 1945 CRANE AND THE LIKE LOAD LIFTING APPARATUS Y E N R O T T A Jan. 30, 1945.

Patented Jan. 30, 1945 CRANE AND THE LIKE LOAD LIFTING APPARATUS Philip Spiegel, Bronx, .N. Y.

Application January 4, 1943, Serial No. 471,242

18 Claims.

This invention relates to cranes and the like load lifting apparatuses. More particularly, the invention pertains to an automatic safety counterbalancing mechanism for preventing toppling of such apparatuses,

The prime object of my invention is to provide a mechanism of the character described which is efficient and fool-proof in use, and can be depended upon to remove the overturning hazards heretofore present in the operation of such apparatuses.

A secondary, but important, object of the invcntion is to provide a practical mechanism of the character described which. by automatically removing the overturning hazards, greatly increases the capacity of such an apparatus.

Another object of the invention is to provide a mechanism of the character described which will act faster than the load can be changed on the apparatus with which it is used, whereby toppling is prevented upon occurrences of sudden changes in load.

A further object of the invention is to provide a mechanism of the character described which will lend itself readily to incorporation in existing crane and the like designs and which can be added as an improvement to such apparatuses in the field.

An additional object of the invention is to provide a mechanism of the character described which will freeze all apparatus controls having to do with movement of a load when a predetermined danger point leading to the toppling of the apparatus is reached, but which permits manual nullification of frozen control for raising Or lowering the load in order to stabilize the apparatus.

Still another object of my invention is to provide a mechanism of the character described which comprises relatively few and simple parts, which is economical to manufacture and install. and which is simple in operation and highly efficient in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out,

The invention accordingly consists in the fcalures of construction. combinations of elements. and arrangement of parts which will be exemplifind in the construction hereinafter described. and of which the scope of application will be indicated in the claims.

In the accompanying drawings, in which is shown one of the various possible embodiments of this invention.

Fig. l is a side elevational view of a crane having my invention incorporated therein;

Fig. 2 is an enlarged sectional view taken substantially along the line 2-2 of Fig. 1;

Figs. 3 and 4 are highly enlarged sectional views taken substantially along the lines 33 and 44, respectively, of Fig. 2; and

Fig. 5 is a partially schematic diagram of the control and actuating circuits employed in my invention.

Referring to the drawings, I have there shown a gantry crane ID of conventional design, comprising a trestle section 12 having a plurality of wheels M at its base. Certain of the wheels, as i well known, are power-operated for traction. These wheels may ride on steel rails l6, securely mounted upon a permanent foundation. A cab I8, supported by the trestle section I2, is arranged to rotate relative thereto by means of a conventional turntable 20. A suitable driving mechanism, such as a gear and pinion, may be provided to turn the cab. A boom 22 is pivotally mounted upon the bed of the cab and carries at its free end a plurality of sheaves 24, 26 adapted to support various lifting mechanisms such as a multiple sheave 28 or a weighted lifting hook 3U. Winches 32, 34 may be provided to actuate the cables controlling the lifting mechanisms 28, 30 and to lift the boom,

The crane, as thus far described, is wholly conventional, and it will be apparent as the description proceeds that cranes and mechanisms of similar types are as well adapted to be used in conjunction with my invention. It will, therefore, be understood that the foregoing description is in no sense limitative and that the invention can be employed. without departing from the spirit of my invention, in all types of cranes as for example, crawler cranes, locomotive cranesv automotive cranes, boat cranes, derricks, stationary cranes. and, generally, in devices having a boom which rotates about a horizontal axis and which is adapted to lift or release a load. The problem common to all of these devices is that because of the aforesaid angular movement of the boom, loads of the same weight may be disposed at different distances from the pivot point of the boom and therefore will apply different overturning torques or moments. As is well known. the load and its horizontal distance from the pivot point determine the value of this torque and since the two often vary rapidly and without close control of an operator, it is difficult; for an operator to prevent the torque from rising to an overturning value. In practice therefor, cranes have often overturned.

In accordance with the present invention, I provide a counterbalance and an automatic mechanism for varying the position thereof relative to the cam, such that very small angular deviations of the crane from its normal or horizontal position will cause the counterbalance to move and increase the stability of the crane by reducing such deviation. Such mechanism is preferably electrically controlled o that it will be responsive to angular deviations of a much lesser degree than are required to actuate mechanical controls, such as clutches, with positive effect. The electric control is also extremely simple to install and service, positive and durable in operation, light in weight, inexpensive to purchase and assemble. Further, it consists of very few parts which are not subjected to high operating stresses so that it gives little trouble in use.

In the illustrated embodiment of the invention the counterbalance comprises a concentrated massive-weight-36 which is securely connected to the ends of two parallel spaced I-beams 38. said beams are slidably received on rollers 40 engaging their upper and lower flanges and secured beneath the deck of the cab l8. The beam lie perpendicular to the horizontal axis of rotation of the boom 22. If the weight is heavy enough and its thrust limit long, additional means may be provided to absorb the larger moment at the points of support of the beams on the crane. It will be apparent that as the weight 36 varies its spacing from the tail of the cab IS, the counterbalancing effect thereof will be changed.

Means is therefore provided for thrusting the weight 36 away from or pulling the same towards the cab l8. Such means may be of conventional character, but preferably is of such nature that the weight can be moved towards or away from the cab at a faster rate than that at which the load applied torque can be altered. This will depend, of course, upon the nature of the use to which the crane or lifting apparatus is put. For example, if the crane is always to take up a load slowly or to put the same down slowly through a device such as the multi-sheave mechanism 28, the counterbalance need not move out from or towards the cab very rapidly, but, on the other hand, if the device is adapted to quickly release loads, as for example a crane or steam shovel which has a trigger release in the cab to suddenly dump a load, the mechanism for moving the weight 36 must. be so constructed that the weight can quickly be moved to counterbalance the sudden imposition or release of a load.

In the accompanying drawings I have shown a weight actuating mechanism of the latter type, that is, one which is capable of moving the weight 36 with extreme rapidity, it being understood. however, that the invention is not to be limited to this type of mechanism. Such mechanism comprises a pneumatic cylinder 42 anchored beneath the deck of the cab [8 between the rollers 40 which constrain the I-beams 38. A piston 44 reciprocates in said cylinder and is attached by a shaft 46 to the counterweight 36. A conventional stuffing box 48 seals the end of the cylinder 42 through which the shaft passes. The two ends of the cylinder are provided with conventional inlet fittings 50 so that air under pressure can be admitted to either ide of the piston 44. It will thus be seen that when it is desired to overcome the effect of too great a load or too extended a position of the boom 22, it is merely necessary to iii) admit air under pressure to the right hand side (as viewed from Fig. 2) oi. the cylinder 42, whereupon the piston 44 will be forced to the left extending the counterweight 36 and stabilizing the crane. The speed at which a system. such as above described, can operate even massive counterweights is so rapid that even if a large load is suddenly released the counterweight will move from its most extended position back to its position closest to the cab before the crane has had a chance to tip dangerously.

To admit air under pressure to either side of piston 44 there is provided a four-way valve 52, Figs. 2 and 5) comprising a valve body 54 havin four outlets 56 equiangularly spaced therearound. The valve plug 58 has two passageways 60, the openings of which are so arranged that in certain positions of the valve adjacent outlets 56 in the valve body are connected to each other. A pair of pipes 62 connect one pair of diametrically opposite outlets in the valve body to opposite ends of the cylinder 42. One of the remainin pair of outlets 56 is connected by a pipe 64 to a source of air under pressure and the last outlet 56 is connected to the atmosphere by a pipe 66. A handle 68 is provided to oscillate the valve plug 58. It will be seen that when the handle 68 i in the extreme position shown in Fig. 2, air will be admitted under pressure on the right hand side of the piston 44 causing said piston to move towards the left and the weight 36 to be extended. If the handle 68 is turned 90 clockwise (as viewed from Figs. 2 or 5) air will be admitted to the left hand side of said piston and pull the weight 36 towards the cab 18. When the handle 68 assumes the position shown in Fig. 5, intermediate the two previously described positions, air under pressure will be admitted to neither side of the piston and the piston will tend to remain stationary.

To make certain that the counterweight does not shift unless the valve handle 68 is at one of its two extreme positions, suitable braking means 69 is provided. Such means may cooperate with the shaft 46 or an auxiliary parallel shaft extending from the counterweight 36 and may comprise a pair of brake bands 10, each of which is fixed at one end to a stationary post 12 at one side of the shaft 46 and at the other end to oppositely disposed arms of a rotary plate 14 on the other side of said shaft. Said plate is mounted on a shaft 16 having a lever 18 secured thereto. The

lever is urged in a counter-clockwise direction as viewed from Fig. 5) by a spring to normally bind the brake bands 10 around the shaft 46 or auxiliary shaft and hold the counterweight in any given location.

Further in accordance with my invention, I provide electrically actuated means to operate the valve 52 and the brake 69, and electric control means to render the electrically actuated operating means eifective or ineffective as conditions may require. The term control, as used herein, denotes a means capable of rendering a mechanism ineffective or effective. It includes means which switch mechanisms off and on, wherein in on position the mechanism may operate in the same or opposite directions, or at the same or different speeds. As thus defined, it will be apparent that control means may include relays, rheostats, electrically operated latches, etc.

The electric actuating means for the valve 52 comprises a solenoid 82 whose actuation causes I the weight 36 to be moved towards the cab i8 and which will hereinafter be referred to as the "retracting" solenoid. Said means also includes a second solenoid 84 whose actuation will cause the weight 36 to be moved away from the cab I8 and which will hereinafter be referred to as the thrusting solenoid. The movable armatures of these two solenoids are connected to each other by a shaft 88. Said shaft carries a pin 88 which is slidably received in a slot 90 in the valve handle 68. The handle is normally maintained in a neutral position intermediate the two extremes of the actuating positions of the valve by means of a centering device. comprising a bifurcated yoke 92 which is pivoted at 94 and which straddles the pin 88 on opposite sides of the cnnecting shaft 86. A short spring 98, connected at one end to a stationary post and at the other end to the yoke 92, biases said yoke to a normally vertical position and therefore normally maintains the connecting shaft 86 centralized between the thrusting and retracting solenoids with the valve handle 68 in neutral position. Power for the two solenoids 82, 84 is derived from electric supply lines 98, I00. The solenoid B2 is connected to said lines by wires I02, I04, and I06 through the fixed contact I08 and normally open armature IIO of relay H2. The solenoid 84 is connected to said lines by wire H4, H6, and IIS through the fixed contact I20 and normally open armature I22 of relay I24.

The electric actuating means for the brake 59 comprises a pair of brake solenoids I26, I28, whose armatures are harnessed together so that either solenoid upon actuation will pull the brake lever 18 against the spring 80 to release the brake 69. These solenoids also derive their power from the lines 98, I00. The solenoid I26 is connected thereto through wires I30. I32 and I06 as well as through the armature of the relay H2. The solenoid I28 is connected to said lines through wires I34, I36, and H8 as well as through the armature of the relay I24.

The electric control means for governing the operation of the foregoing electric actuating means is responsive to angular deviation of the cab I8 or trestle I2, or both, depending upon where it is desired to control such deviation from normal or horizontal position, that is. the control means will, when the crane structure supporting it .reaches a predetermined angular deviation, become operable, and will become inoperable when said crane structure returns to a smaller angle. as for example back to normal or hori- Zontal position. Said means. furthermore, is preferably responsive to tilting in the plane including the boom 22 and counterweight 38. Accordingly, the control means is usually mounted upon the structural element. as for example the cab I8. which revolves with or supports the boom 22 during turnin thereof about a vertical axis and is so oriented as to be responsive to tilting in said plane. Further, said means must be selectively sensitive to tipping of the said supporting structure in either a clockwise or counterclockwise direction. In other words, it must so control the operation of the means for moving the counterweight 35 toward or away from the cab that said counterweight will move toward the cab when its extended position tends to topple the crane. or away from the cab when the moment of the load carried by the boom tends to topple the crane.

The electric control mean for the retractin solenoid 82 comprises a mercury tilt switch I38. including a glass envelope I40 having a pool of mercury I42 contained therein. One end of said envelope supports a pair of spaced contacts I44 which are adapted to close the energizing circuit for the solenoid I46 of the relay II2 from the supply lines 98, I00 through wires I48. I50, and I52. The envelope I40 is supported in a pivot clamp I54 at one end and caught at the other end between the tips of screws I56. Those screws are so adjusted that when the cab I8 isin a horizontal position the envelope is inclined'to the horizontal at a predetermined angle which it is desired not to have the crane exceed when releasing a load. In a gantry crane of the type illustrated the angle of permissible tippin should be kept very small, as for example about three degrees. The mercury tilt switch I40 is so arranged that when this angle is reached or very slightly exceeded, the pool I40 will submerge the contacts I44 therein to complete the control cir cuit for the relay H2. The mercur tends to adhere to said contacts I44 and will not leave the same until movement of the counterbalance causes the crane to assume a lesser angle, as for example to become restored to substantially normal or horizontal position. The tendency for the pool of mercury to adhere to the contacts I44 may be increased or decreased by varying the space between said contacts. so that where substantially different degrees of angular inclination are to be permitted prior to actuation of the counterweight 3G or where it is desired to vary the angular inclination at which the control means is rendered inoperable, mercury relays I38 having difierent spacings between the contacts I44 may be employed.

The thrusting solenoid is controlled by another mercury tilting relay I54 which is connected to the supply lines by wires I58, I58, and I06. Said relay is in all respects s milar in its construction and mounting to the relay I38, but is inclined at an opposite angle to the horizontal so as to energize the thrusting solenoid I54 when the boom is subjected to too great a moment. Obviously the angles of the two relays I38. I54. although opposite. need not be of identical absolute values.

It will be seen that when either of the mercury tilting switches I38, I54 is closed the solenoid of its associated relay II2, I24 is energized to close the corresponding armature H0. I22 against the fixed contact I08, I20; this action. in additionio energizing the proper solenoid 82, 84, will also energize one of the brake solenoids I26, I28 to release the brake 69 when the valve handle 68 is turned. Normally the brake. because of its lighter mass. will respond more quickly to actu ation than the counterweight 36. ll. however. the counterweight tends to move before the brake is released. any standard type of electric or mechanical delay may be interposed in the mechanism for controlling or actuating movement of the counterweight 36. Such mechanisms may in clude dash-pot relays. thermal-delay relays. chokes, or the like.

Since a Crane or s milar load lifting apparatus equipped with my automatically operating counterweight 36 would be handled with less caution by a crane control man than is now maercised. and ince it is possible for a mechanical or electrical defect to appear in either the control or actuating mechanisms. it is important that in conjunction with the various means [or automatically operating said counterweight there also be provided safety means for stopping all normal crane manually controlled operations it the deviation of the crane from the horizontal substantially exceeds the deviation at which the mercury tilt switches I38. I54 are supposed to initiate operation oi the counterweight 36. This necessity for this safety means may be due either to defective control mechanism or to the fact that the crane has picked up too heavy a load, for which even the counterweight 36 cannot compensate. Such safety means comprises a mercury tilt control switch I62 which includes a glass envelope I64 whose two ends are oppositely inclined. The relative angular relationship between these two ends is equal to twice the permissible safe angular deviation of the crane from the horizontal. Said envelope is mounted in the cab with the twe ends thereof in the plane of the boom I22 and counterweight 36 and. when the Cab is in normal or horizontal position, inclined at equal angles to the horizontal. The envelope contains a pool I66 of mercury and the two ends have pairs of contacts I68 secured therein and extending into the envelope I64. It will thus be apparent that, when the crane tip in either direction beyond a predetermined safe deviation from the horizontal. the mercury pool I66 will close the space between one of the pairs of contacts 68.

The control circuit governed by said switch I62 includes a relay I'll] whose solenoid I'iI is connected to the supply line I by a wire I12. The other end of the solenoid I'Ii is connected by wires I14, I16 to one contact of each pair of contacts I68. The other contacts of said pairs of contacts are connected by wires I78, I86, and I82 to supply line 98.

The actuating circuit governed by the aforesaid safety control comprises a turntable control I84, a traction control I86 for the wheels I4. a boom control I68, that is a control for the angular position of the boom above the horizontal, and a winch control I90. The foregoing controls are connected by wires i922i2, fixed contact 2M of relay I70, and normally closed armature 2I6 thereof to the power supply line 98, IIJIJ. The wires connecting the traction control and turn table control I84, I86 to the source of power include a double-pole, single-throw switch 2I8 which in the normal operation of the crane is closed.

It will be seen that when closing of the tilt witch I62 energizes the solenoid I70 and attracts the armature 2 I6, the source of power is removed from the winch, boom, traction and turntable controls. thus freezing all operation of the crane which is liable to further add to the overturning moment. Of course. when these operations are frozen the crane man will recognize that danger is imminent. or if desired. a horn or some similar danger signal may be energized by movement of the armature 2 I 6.

When the armature 2I6 is opened, the crane operator opens the switch 2I8 which is designed to leave all controls open which cannot be readily manipulated to reduce overturning momentum. He then closes a switch 220 which is open during normal crane operation. Closing of this switch again supplies current to the winch and boom controls from the supply lines 98. I00 through auxiliary feed wires 222, 224. and 226, so that the operator can manipulale either the winch or boom to reduce the overturning moment and restore the crane to stable equilibrium.

It may be mentioned that the foregoing winch. boom. traction, and turntable controls may be the operating rheostats for these elements of the crane if the crane is electrically powered, and in this event, the controls represent the means for varying the speed and direction of operation of said elements. In addition controls of this type.

. i. e., controls in electrically powered cranes, in-

elude brakes oi conventional character which are normally held in inoperative position but which. when electric power is cut oil by action of solenoid I10, become operati e to prevent movement of the boom, traction wheels, winch. turntable, etc. Thus stopping" as applied to the foregoing controls also include a locking function. Where the crane or load lifting apparatus is motivated b other sources of power, as for example steam. the winch. boom, traction, and turntable controls may take other forms, as for example, of electrically controlled clutches and latches, or brakes which permit operation of the various crane elements, under normal conditions, being held in proper position for this effect by suitabl means, as for example, solenoids which are energized when the mercury tilt switch I62 is open and whose actuating members are spring pressed to stop and lock movement of the several crane operating elements when the tilt switch I62 is closed.

It will be understood. of course, that the specific crane operating elements mentioned need not be the only elements governed by the safety means and that any crane element whose operation might affect the turning moment should be included in the above circuit and thus rendered inoperative when the tilt switch I62 is closed.

It will thus be seen that there is provided a device which achieves the several objects of this invention and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention and as various changes might be made in the embodiment above set forth. it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention. I claim as new and desire to secure by Letters Patent:

1. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure, and electric control means operable in response to a predetermined deviation of said structure from normal to render said last named means efl'ective while said structure is at least so deviated.

2. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combina tion of a counterweight supported for movement relative to said structure, means to more said counterweight towards and away from said structure, and electric control means operable in response to a predetermined deviation of said structure from normal to render said last named means effective, said control means being rendered inoperable. whereb said counterweight actuating means is rendered ineffective, when movement [1f said counterweight causes said structur In assume a lesser deviation from normal.

3. For use with a devi e having a load llillZClIillgI boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure. means to move said counterweight towards and away from said structure, and electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said last named means effective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered ineffective, when said structure returns substantially to normal horizontal position.

4. For use with the device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure, electrically actuated means to govern the operation of said counterweight moving means, and electric control means operable in response to a predetermined deviation of said structure from normal to render said electrically actuated means effective to initiate operation of said counter-weight moving means, said electric control means being rendered i ope e, where y said counterweight moving means is rendered ineffective, when movement of said counterweight causes said structure to assume a lesser deviation from normal.

5. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move sa d counterweight towards and away from said structure, electrically actuated means to govern the operation of said counterweight moving means, and electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said electrically actuated means effective to initiate operation of said counterweight moving means, said control means being rendered inoperable, whereby said counterweight moving means is rendered ineffective when movement of said counterweight causes said structure to assume a lesser devia tion from the horizontal.

6. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said struc ture, electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said last named means efiective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered ineffective, when said movement of said counterweight causes said structure to assume a lesser deviation from the horizontal, and means to selectively vary said predetermined deviation.

" 7. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure, electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said last named means effective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered ineffective, when movement of said counterweight causes said structure to assume a lesser deviation from the horizontal, and means to maintain said 1 from normal horizontal position to render said last named means effective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered ineffective, when movement of said counterweight causes said structure to assume a lesser deviation from the horizontal, and braking means to maintain said counterweight stationary when said control means is inoperable.

9. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure, electrically actuated means to govern the operation of said counterweight moving means, electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said electrically actuated means effective to initiate operation of said counterweight moving means, said control means being rendered inoperable, whereby said counterweight moving means is rendered ineffective, when movement of said counterweight causes said structure to assume a lesser deviation from the horizontal, braking means to maintain said counterweight stationary when said control means is inoperable, and electrically actuated means to render said braking means inefiective when said control means is operable.

10. For use with a device having a load handling boom which turns about a horizontal axis and which is supported by a structure: the combination of a counterweight supported for movement relative to said structure, pneumatic means to move said counterweight towards and away from said structure, and electric control means operable in response to a predetermined deviation of said structure from normal horizontal position to render said last named means effective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered inefiective, when movement of said counterweight causes said structure to assume a lesser deviation from the horizontal.

11. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, means to turn said boom about a vertical axis, a counterweight supported for movement relative to said structure means to move said counterweight towards and away from said structure, electric control means operable in response to a predetermined' deviation of said structure from normal horizontal position to render said last named means effective, said control means being rendered inoperable, whereby said counterweight actuating means is rendered ineffective, when movement of said counterweight causes said structure to assume a lesser deviation from the horizontal, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, and electrically actuated means operable in response to a larger predetermined deviation of said structure from normal horizontal position to cause said second named control means to render the means controlled thereby inoperable.

12. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, a plurality of separate control means for said means for turning said boom about a horizontal axi and for said means for independently raising a load, and means operable in response to a predetermined deviation of said structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable.

13. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, means to turn said boom about a vertical axis, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, and means operable in response to a predetermined deviation of said structure from normal horizontal position to cause said control means to render the mean controlled thereby inoperable.

14. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, mearis independent of said last named means for raising a load, means to turn said boom about a vertical axis, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, and electrically actuated means operable in response to a predetermined deviation of said structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable.

15. In combination, a load handlin boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, means to turn said boom about a vertical axis, a counterweight supported for movement relative to said structure, means to move'said counterweight towards and away from said structure to counterbalance deviations of a predetermined degree of said structure from normal horizontal position, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, and means operable in response to a larger predetermined deviation of such structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable.

16. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, means to turn said boom about a vertical axis, a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure to counterbalance deviations of a predetermined degree of said structure from normal horizontal position, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, and electrically actuated means operable in response to a larger predetermined deviation of said structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable.

17. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raisin a load, means to turn said boom about a vertical axis, a counterweight supported for movement relative to said structure, means to move said counterweight to wards and away from said structure to counterbalance deviations of a predetermined degree of said structure from normal horizontal position, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, electrically actuated means operable in response to a larger predetermined deviation of said structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable, and manually manipulative means to render either the means for turning said boom about a horizontal axis or the means for independently handling a load operable after they have been rendered inoperable by the control means.

18. In combination, a load handling boom which turns about a horizontal axis and which is supported by a structure, means to turn said boom about said axis, means independent of said last named means for raising a load, means to turn said boom about a vertical axis, a counterweight supported for movement relative to said structure, means to move said counterweight towards and away from said structure to counterbalance deviations of a predetermined degree of said structure from normal horizontal position, a plurality of separate control means for said means for turning said boom about a vertical axis, for said means for turning said boom about a horizontal axis and for said means for independently raising a load, electrically actuated means oprable in response to a larger predetermined deviation of said structure from normal horizontal position to cause said control means to render the means controlled thereby inoperable, and manually manipulative means to render the means for turning said boom about a horizontal axis and the means for independently handling a load operable after they have been rendered inoperable by the control means.

PHILIIJ SPIEGEL.

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