GB2025362A - A device for controlling adjusting rings on a rotary frame of turntable apparatus - Google Patents

Abstract

A ladder (2) is pivotally mounted at 5 on a turntable (3), the turntable being rotatably mounted on a vehicle (1) by means of a bearing system (6) comprising bearing rings which can be adjusted to maintain the rotational axis (4) of the turntable (3) vertical even if the vehicle (1) stands on sloping ground. The rotation of the bearing rings is effected by motors controlled by a directional balance (22) and a compensating balance (23) mounted on one of the rings (13) which is rotatable about an oblique axis (17). The measuring direction of the directional balance (22) extends parallel to a vertical plane (24) containing the oblique axis. <IMAGE>

Description

SPECIFICATION A device for controlling adjusting rings on a rotary frame of turntable apparatus This invention relates to a device for controlling adjusting rings on a rotary frame of turntable apparatus -- for example, a turntable fireman's ladder or other rescue appliance.

Certain rescue appliances include a turntable mounting an extensible ladder, an extensible boom or the like, the turntable being rotatably mounted on a vehicle by way of bearing rings, which rings are rotatably adjustable for maintaining the axis of rotation of the turntable vertical even when the vehicle is standing on sloping ground. One adjusting ring can be rotatable around the vertical axis of the vehicle underframe, and the other adjusting ring can be rotatable with respect to the first ring around an oblique axis at an angle to the vertical axis of the underframe, the rotation being brought about by motors, using a directional balance and a compensating balance extending at an angle to the directional balance.

The present invention is particularly concerned with a device for controlling the adjusting rings.

British Patent Specification No. 1,487,935 discloses a device for vertically aligning the vertical axis of a transportable turntable ladder, the device comprising two coaxially interlocking bearings, one associated with the rotary frame and the other with the underframe of the ladder and the two bearings being pivotably connected along an inclined axis of rotation. It is also stated that the rings of the bearings are manually or automatically moved via suitable control and regulating devices for vertically aligning the vertical axis, but the Specification does not disclose the technical details of the ring control system.

In another known device (German Auslegeschrift 1 7 00 878), the directional and compensating balance are disposed on the turntable, the measuring direction of the directional balance extending parallel to the longitudinal axis of the turntable and the measuring direction of the compensating balance extending at an angle thereto. The turntable is vertically aligned in a number of successive operations.

In the first step of the aligning process, the structure is rotated around the vertical axis of the underframe clockwise until the longitudinal directional balance is vertical and the region of the structure to which the directional balance is attached extends towards the descending side of the ground. Next, the structure is held in the aforementioned position by an upright which can be lowered on to the ground. Next, the adjusting rings, which have been reciprocally locked in their normal position, are rotated together until their oblique axis coincides with the longitudinal axis of the structure, which is indicated by a limit switch which can stop the motion of the adjusting ring.

Finally, the adjusting rings are rotated in opposite directions until the compensating balance and consequently the vertical axis of the turntable are vertical. One disadvantage of this arrangement is that the control of the adjusting rings is dependent on the position of the structure relative to the slope. This restricts the use of the device, since the structure cannot be vertically aligned in cases where it cannot be transversely positioned, e.g. in towns with narrow streets. Another disadvantage is that the device is made unnecessarily complicated and expensive owing to the additional uprights for securing the structure. A final disadvantage is that a number of operations are necessary for aligning the structure, which unnecessarily delays the time when the device comes into action.

An aim of the present invention, therefore, is to provide a means of controlling the actuating rings so as to obviate the disadvantages of the prior-art controls.

To this end, according to the invention, the directional balance and the compensating balance are disposed at the adjusting ring which is rotatable around the oblique axis, the measuring direction of the directional balance extending parallel to the vertical plane containing the oblique axis.

An advantage of the inventive improvement of the device is that the control of the adjusting rings is independent of the position of the structure relative to the slope, so that the structure does not need to pivot, thus eliminating one operation.

Another advantage is that the upright for locking the structure can be omitted, which reduces the cost of the structure and also eliminates a second operation.

According to a preferred embodiment of the invention which is important with regard to the monitoring of the control system and for the individual operations, when the turntable ladder is in its stowed transport position, the adjusting rings are secured by an abutment in a normal position in which the oblique axis is at a maximum angle of a to the vertical axis of the underframe. In this embodiment, a switch can be provided at the abutment, whereby the two motors for moving the adjusting rings into the basic position can be actuated in the same or in opposite directions.

In order to control the adjusting rings in substantially automatic manner, the directional balance can have contacts at its end, the contacts being disposed in a first control circuit via which the motors of the adjusting rings can be actuated around the vertical axis of the vehicle simultaneously in one or the other direction of rotation.

To avoid delays, the adjusting rings are preferably actuated simultaneously with other operations which are important in bringing the ladder or the like into action. To this end, the first control circuit contains a switching contact coupled to a handle for actuating the uprights, and when the uprights are retracted, the contact breaks the current supply to the directional balance. This also prevents incorrect operation of the ladder.

According to the standard specifications in force, rotary ladders must not be brought into operation until the ladder system has been horizontally aligned. This means that the ladders must be aligned mainly in the transport position.

Since the ladder moves around its longitudinal axis during aligning, it may damage the mounting or the driver's cab. To avoid this, the control system according to the invention can be constructed so that the contacts of the compensating balance are disposed in a second control circuit containing a safety switch which is upstream of the compensating balance in the direction of current flow, is open when the ladder is in the transport position, and does not switch over to the closure position until the ladder has been raised from its mounting.

The control system is preferably constructed so that the individual motions of the motors or rings are successively controlled via a stepping switch system.

In one embodiment the compensating balance has only one contact which can be actuated either via a stepping switch system or directly in dependence on the position of the directional balance to the slope, by pivoting the directional balance through 1800. However, if a compensating balance with two contacts is used according to the invention, the second contact can serve as a reversing switch-for rotating the adjusting rings through 1800 to a new position.

According to another embodiment of the invention, a different kind of inclination-measuring device is used, irrespective of the previouslydescribed possible methods of actuating the motors used for rotation. Optionally, for example, a round level having a polar scale is provided as an inclination and directional balance and mounted on the rotary frame and has a contact ring at its outer periphery for determining the position of the slope, the ring being connected to a second contact ring on the underframe, the individual contact points on the two contact rings marking identical directions relative to the various vehicle axes and a sensor being movable past the contact ring at the underframe, the sensor being secured to a ring and offset 900 relative to the oblique axis, and used via the stepping switch system to actuate the motors used for rotation.

The round level can be constructed so that the contact ring comprises a single contact segment which is pivotable in synchronism with the adjusting rings rotating in the same direction, the position of the segment on the contact ring being offset by 900 relative to the position of the oblique axis.

Three different embodiments of the invention are shown by way of example in the accompanying drawings, in which: Figure 1 shows the adjusting-ring control system, comprising a compensating balance and a directional balance and an electronic stepping switch; Figure 2 shows the adjusting-ring control system according to claim 1 but with additional control equipment and without a stepping switch, and Figure 3 shows an adjusting-ring control system according to claim 1 , with a mechanical stepping switch system and a round level used to measure the inclination and as a pulse transmitter for the control equipment.

An extensible ladder 2 is pivotably mounted by its base on a frame 3 for pivoting about an axis 5 which is to be adjusted to be horizontal. The frame 3 comprises a turntable which is rotatable about an axis 4 which is to be adjusted to be vertical. In order to ensure that axis 4 can be adjusted to be vertical when the vehicle 1 is on a slope, a compensating device 6 is provided between the rotary frame 3 and the bearing means on vehicle 1. Downwardly extensible supports 7 are provided on the vehicle frame, preferably in front of and behind the rear axle, for rigidly supporting the vehicle on the ground. During transport, ladder 2 is stowed in a mounting 9 behind the driver's cab.

The compensating device 6 has two coaxial ball bearings 10, 11 each with an outer adjusting ring 12, 13 and an inner adjusting ring 14, 15. The inner ring 14 of bearing 10 is connected to the outer ring 13 of bearing 11 via a main bearing 1 6 so that it can pivot around an oblique axis 17. The oblique axis 17 is at an angle crto the axes of rotation of the two bearings; the angle is at a maximum when bearings 10, 11 are in the normal position and the two axes of rotation of bearings 10, 11 coincide. The normal position of bearings 10, 11 is shown in section in Figures 1, 2 and is held by an abutment 18 between rings 13 and 14.

The individual motion of rings 13, 14 and the pivoting of ladder 2 around axis 4 are brought about by three special motors, indicated by 19, 20 and 21 in the control diagram in Figure 1.

Motors 19, 20 are for driving rings 13 and 14, i.e. motor 19 drives ring 14 and motor 20 drives ring 13. Motors 19, 20 are both mountetl on vehicle 1 and are connected by worm drives or the like to gear rims on rings 13 and 14. Motor 21 is mounted on the rotary frame 3 and is used for pivoting ladder 2around the vertical axis 4 and also for balancing the rotation relative to motor 20 during the aligning phase. Alternatively, motor 21 can be mounted on vehicle 1, in which case there is no need to equalize the rotation.

Oblique positions of the vehicle are measured by using mercury contact tubes cons,tructed like spirit levels; in accordance with their operation, they will be described as a "directional" balance 22 and a "compensating" balance 23. The two balances are disposed on ring 13. In order to show the exact position of balance 23 and 22 on ring 13, the ring is shown diagrammatically in plan view as a circle in the circuit diagrams in Figures 1 and 2. A chain-dotted-line in the circle shows a horizontal line lying in the vertical plane 24 in which the oblique axis 1 7 lies, and the lowest point of the ball-race of the main bearing 16 is shown as a point of intersection 25.

The directional balance 22 has a contact pair 26, 27 at each end and is disposed at ring 13 so that contacts 26, 27 and consequently their measuring direction lie parallel to the plane 24 containing the oblique axis 1 7. The compensating balance 23 has only one contact 28 and is disposed at ring 23 so that its measuring direction is vertical, i.e. at 900 to the direction of plane 24.

In order to actuate the motors 19 21, balance 22 and balance 23 are disposed in two electric control circuits 29, 30. A third control circuit 31 ensures that the adjusting rings are returned to neutral position after operation. Circuits 29 - 31 are connected to an electronic stepping switch 32 connected to the main current conductor 33 of the vehicle. Conductor 33 also supplies current to motors 19-21.

Contacts 26 and 27 of balance 22 are connected to the first control circuit 29. A conductor 34 extends from contact 26 to a switching relay 35 on motor 19, a switching relay 36 on motor 20 and a switching relay 37 on motor 21. A line 56 connects contact 27 to switching relays 39, 40 and 41. By means of relays 35 and 36, motors 19 and 20 are rotated in the same direction, e.g. counterclockwise, whereas motor 21 is rotated via relay 37 in the opposite direction, i.e. clockwise. Contact 28 of balance 23 is disposed in the second control circuit 30, which is coupled via a conductor 38 to relays 35 and 39, 40 in order to drive rings 13, 14 in the opposite direction.Consequently, motor 1 9 is driven counterclockwise via control circuit 30, motor 20 is driven clockwise and motor 2i is driven counterclockwise, Rings 13 and 14 are automatically rotated back to neutral position by a switch 42 in control circuit 31 disposed at abutment 1 8 between rings 13 and 14.

The electronic stepping switch 32 has a fourth control circuit, i.e. a line 43 connected to motor 21 for pivoting ladder 2. Although not shown, the electronic stepping switch 32 automatically sets the individual control operations. The control sequence is as follows: After a main switch 44 has closed, the main conductor 33 supplies current to the control motors 19, 21 and the stepping switch 32. The energy arriving at switch 32 generates a control pulse which initially checks whether rings 13, 14 are in the neutral position. Then, and only then, a connection is made in switch 32 between conductor 33 arki the first control circuit 29. If vehicle 1 is on a slope, the mercury ball in balance 22 will be a contact 26 or 27. In the present case it is assumed that the mercury ball is at contact 26.

The first control circuit 29, via contact 26 and conductor 24, actuates relays 35, 36 and 37.

Rings 13 and 14 both move anticlockwise. Motor 21 is driven clockwise via relay 37 and thus compensates the rotation. Rings 13 and 14 are both rotated until the directional balance 22 is horizontal, thus determining the direction of the slope relative to the vehicle. In the last-mentioned position, the imaginary directional vector of the slope is at right angles to the measuring direction of balance 22 and simultaneously parallel to the measuring direction of balance 23. Next, the electronic stepping switch 32 automatically releases the second control circuit 30 and thus, via contact 28 at balance 23, moves rings 13 and 14 in opposite directions via motors 19 and 20 until the vertical axis 4 is vertical. If the mercury balls are at the contactless end of the compensating balance, stepping switch 32 moves rings 13 and 14 in the same direction through 1800 to a new position.

After the vertical axis 4 has been aligned, switch 32 releases the control circuit 43 for rotating ladder 2. In order to transport the ladder 2, the adjusting rings are then returned by switch 32, via control circuit 31, into the neutral position.

In the control circuit in Figure 2, motors 19 21 are connected, in similar manner to the control system in Figure 1, to a directional balance 45 and a compensating balance 48 which are disposed at the adjusting ring 13 in the same manner as the directional balance 22 and compensating balance 23 in Figure 1. The directional balance 45 comprises two mercury contact tubes each having only one contact 46, 47. In addiction to the compensating balance 48 and its contact 49, a further mercury contact tube is disposed in the same measuring direction at ring 13 and its contact 51 is placed at the mirror image of contact 49 relative to plane 24.The mercury contact tube acts as a reversing switch 50, which rotates rings 13, 14 in the same direction through 1800 so as to bring the contact 49 into the correct switching position if the slope is at one side.

The control system comprises four control circuits 52 - 55 for automatically aligning axis 4; vertically. Circuit 52 comprises balance 45 having contacts 46, 47 and switch 50 having a contact 51. A switch 57 actuated by contact 47 prevents faulty operation of motors 19 -21, The compensating balance 48 is disposed in the second control circuit 53 as in Figure 1.Circuits 54 and 55 ensure that the adjusting rings are brought to their normal position before each aligning operation and after operation of the ladder has finished. To this end, a switching element 58 is disposed in the main conductor 33 connected to the individual circuits 52 - 55.

Element 58 is simultaneously actuated by abutment 18 at rings 13 and 14, via switching elements 59 in the two control circuits 54 and 55.

When rings 13, 14 are in the neutral position, element 56 is closed and elements 59 are open.

A switching contact 60 is incorporated in circuit 53 in front of contacts 46 and 47 and actuated by a control lever 61 for extending and retracting the uprights 7. Contact 60 is open when uprights 7 are retracted and is not closed until the uprights 7 are extended by means of lever 61. This can shorten the time for aligning the vertical axis 17, since the control operation of determining the direction of the slope can proceed via the directional balance 45 at the same time as the uprights 7 are being extended. Uprights 7 are also coupled to a safety switch 62 such that the control circuit 53 (for compensating the slope) cannot be coupled to the main conductor 33 unless all uprights 7 are properly in contact with the ground. In the position shown in continuous lines, switch 62 connects only the control circuits 52 and 55 to the main power circuit 33.When all uprights 7 are properly in contact with the ground, switch 62 changes over to its second position, so that circuits 52 and 55 are disconnected from the main conductor 33 but circuit 53 is connected thereto. In the resulting connection between conductor 33 and circuit 53, an additional switching relay 63 is provided between contact 49 and switch 62. Relay 63 is constructed so that it can alternately connect or disconnect circuit 53 or 54 to or from conductor 33. Relay 63 is thus designed to prevent mounting 9 or cab 8 from being damaged by the motion of ladder 2 around its longitudinal axis when axis 17 has been vertically aligned. Accordingly, relay 63 in the control system is switched so that circuit 53 is disconnected from conductor 33 as long as the ladder 2 is in mounting 9.When, and only when, ladder 2 has been raised about 20 from mounting 9, relay 63 received a control pulse, e.g. via a switch at mounting 9, and changes over from its normal position (indicated by continuous lines) into the control position (chain-dotted). In the latter position, only circuit 53 is connected to conductor 33, i.e. motors 19 - 21 are driven in opposite directions via contact point 49 until axis 1 7 is vertical.

Figure 3 shows a control system in which a around level 64 having a polar scale is used as an inclination and directional balance. Although not shown in Figure 2, level 64 is mounted on the rotary frame 3 of ladder 2. At its outer periphery, level 64 has a contact ring 65 divided into a number of segments 66 (i.e. 66a - 66d). Ring 65 is connected to a second contact ring 67 having portions 68 (i.e. 89a -- 68d) secured to the vehicle. Segments 66 and segments 68 mark identical directions relative to the various vehicle axes, i.e. segments 66 and 68 or segments 66c and 68c mark the same direction at the vehicle Segments 66 and 68 are interconnected by lines 60.

A sensor 70 can move past segments 68 and is disposed at ring 1 3 or 14 at right angles to the vertical plane 24, so that the oblique axis 1 7 can be brought into a position at an angle to the direction of the slope.

Level 64 has additional contact surfaces 71,72 and 73. Surfaces 71,72 are connected by lines 74, 75 respectively to a stepping motor 76. Motor 76 drives a stepping switch system 77 having control positions 78 - 82. The individual positions 78 - 82 receive control current via a rotatable key 83 connected to the main conductor 84 coming from the vehicle battery. Conductor 84 is also connected to sensor 70, contact surface 73, the motors used for rotation and the stepping motor 76. The stepping switch system 77 actuates the three motors 85 - 87 for rotating the adjusting rings 13, 14 and the rotary ladder 2.

Starting from position 78, motors 85 and 86 are rotated in the same position via relay 88, 89 respectively to determine the direction of the slope and are moved in opposite directions by relays 90 and 91 via position 79 in order to compensate the slope. Position 80 is for rotating ladder 2, using motor 87. In position 81, rings 13, 14 are returned to neutral position by action of relays 88 and 91, and in position 82 the key 83 is in its end position.

The circuit operates as follows: The mercury ball in level 66 is in the position shown in Figure 3. A switch 92 is pressed, thus switching on the position motor 76 and moving key 83 from position 82 to position 78. The result is a connection to relays 88 and 89 of motors 85 and 86, which simultaneously rotate both rings 1 3 and 14, e.g. clockwise, in order to find the direction of the slope relative to the vehicle. In synchronism with rings 1 3 and 14, sensor 70 moves along the contact segments 68 on the second contact ring 67. As soon as sensor 70 touches segment 68d, a control current flows from the battery via sensor 70, line 69, segment 66d, contact surface 71 and line 74 to motor 76, thus rotating key 83 to position 79. In position 79, relays 90 and 89 move motors 85 and 86 in opposite directions to compensate the slope. The motion continues until the mercury ball inside the level moves to the centre and thus makes contact between surface 72 and 73. When this contact is made, a control current flows from the mercury ball via surface 72 and line 75 to motor 76, which moves key 83 into position 80. The control signal also means that the slope has been compensated, i.e. the oblique axis 1 7 is vertical. In control position 80, ladder 2 can be pivoted around the inclined axis 17 by motor 87. After operation of the ladder has ended, rings 13 and 14 must be pivoted back into neutral position. To this end, a switch 97 on motor 76 is actuated, thus moving key 83 into position 81 and pivoting rings 13 and 14 into their neutral position, via relays 91 and 88.

Finally, switch 94 ispressed, causing motor 76 to move key 83 into the end position 82.

Claims (12)

1. A device for controlling adjusting rings on a rotary frame of turntable apparatus, e.g. a turntable fireman's ladder, for vertically aligning the vertical axis of the turntable apparatus rotatably connected to an underframe via the rotary frame, one adjusting ring being rotatable around the vertical axis of the underframe and the other adjusting ring being rotatable relative to the first ring around an oblique axis at an angle to the vertical axis of the underframe, the rotation being brought about by motors, using a directional balance and a compensating balance extending at an angle to the directional balance, in which the directional balance and the compensating balance are mounted on the adjusting ring which is rotatable around the oblique axis the measuring direction of the directional balance extending parallel to a vertical plane containing the oblique axis.

2. A device according to claim 1, in which, when the turntable ladder or the like is in a stowed position for transport, the adjusting rings are secured by an abutment in a normal position in which the oblique axis is at a maximum angle of a to the vertical axis of the underframe.

3. A device according to claim 2, in which switches are disposed at the abutment whereby the motors for moving the adjusting rings can be driven in the same direction or in the opposite direction into the normal position.

4. A device according to any of claims 1 to 3, in which the directional balance has contacts at its end, the contacts being disposed in a first control circuit via which the motors of the adjusting rings can be actuated around the vertical axis of the vehicle simultaneously in one or the other directions of rotation.

5. A device according to claim 4, in which the first control circuit contains a switching contact coupled to a handle for actuating extensible supports, and when the supports are retracted, the contact breaks the current supply to the directional balance.

6. A device according to any of claims 1 to 5, in which the contacts of the compensating balance are disposed in a second control circuit containing a switching relay which is upstream of the compensating balance in the direction of current flow, is open when the turntable ladder or the like is in the stowed transport position, and does not change over to the closure position until the ladder or the like has been raised from its mounting on the driver's cab.

7. A device according to any of claims 1 to 6, in which the motion of the motors and adjusting rings is successively controlled via a stepping switch system.

8. A device according to any of claims 1 to 6, in which the compensating balance has only one contact which can be actuated either directly in dependence on the position of the directional balance relative to the oblique/axis/ or via the stepping switch system by pivoting the adjusting rings through 1800.

9. A device according to claim 1, wherein the compensating balance has two contacts, in which the second contact serves as a reversing switch for rotating the adjusting rings through 1 800 to a new position.

10. A device according to claim 1, characterised in that a round level having a polar scale is provided as an inclination and directional balance and mounted on the rotary frame and has a contact ring at its outer periphery for determining the position of the slope, the ring being connected to a second contact ring on the underframe, the individual contact points on the two contact rings marking identical directions relative to the various vehicle axes and a sensor being movable past the contact ring at the underframe, the sensor being secured to a ring and offset 900 relative to the oblique axis and used via the stepping switch system to actuate the motors used for rotation.

11. A device according to claim 1, characterised in that a contact ring comprises a single contact segment which is pivotable in synchronism with the adjusting rings rotating in the same direction, the position of the segment on the contact ring being offset by 900 relative to the position of the oblique axis.

12. A device substantially as-described herein with reference to Figure 1, Figure 2, or Figure 3 of the accompanying drawings.

1 3. A vehicle in which the vertical alignment of a turntable device, such as a ladder, is controlled by a device according to any preceding claim.