Loading arm with a lock-down device

This invention provides for a spring-balanced loading arm with a positive lock-down device use in a material handling system. It includes a swivel arm which is pivotally connected at one end to a support structure for swivel movement both in horizontal and vertical planes relative to the support structure. There is also provided an extendable lock-down device for positively locking the swivel arm. One end of the lock-down device is pivotally connected to the support structural and the other end is fixedly connected to the swivel arm. The lock-down device is adapted to be locked in position at several predetermined lengths. When the lock-down device is locked in a given position, it also positively locks the swivel arm and prevents any vertical movement of the loading arm.

TECHNICAL FIELD 
The present invention relates to a lock-down device for positively locking 
in a desired position swivelable arms, such as loading arms used for the 
transfer of both wet or dry materials to tank cars or trucks. 
BACKGROUND OF THE INVENTION 
Spring-balanced or weight-balanced loading arms are generally used for 
transferring wet or dry materials into tank cars or trucks. The 
spring-balanced loading arms shown in U.S. Pat. Nos. 3,244,440 issued to 
Albert A. Ashton et al. on Apr. 15, 1966 and U.S. Pat. No. 4,537,233 
issued to Evart J. Vroonland on Aug. 27, 1985 are examples of loading arms 
which are currently in use. These loading arms have a tendency to rise out 
of the truck or tank car loading port during loading because of the force 
of the counterbalance spring or the counterbalance weight and the jet 
action of the material being discharged. For safety reasons, it is very 
desirable to lock the loading arm when it is used for transferring a 
material. Absent any locking mechanism, the loading arm will have an 
unwanted vertical and horizontal movement during loading operations. These 
movements are aggravated when the loading is being done into an open dome 
type tank car or truck. 
In the past, locking devices have been used to lock down the loading arm at 
the riser end of the arm. However, these devices require the loading arm 
operator to move from his position at the loading port to the riser end to 
engage the locking device. Furthermore, these lock-down devices still 
permit a certain amount of movement of the loading arm at the port end. 
The present invention provides a lock-down device which positively locks a 
loading arm into a given position during loading operations. 
SUMMARY OF THE INVENTION 
The invention provides for a loading arm which has a support structure, a 
spring assembly, and a swivel arm having a riser end and a port end. The 
riser end of the swivel arm is pivotally attached to the support structure 
for swivel movement in both the horizontal and vertical planes relative to 
the support structure. The spring assembly is connected to both the 
support structure and the swivel arm to provide balance to the swivel arm. 
The invention also includes an extendable lock-down structure which has a 
lower end and an upper end. The lower end of the lock-down device is 
pivotally connected to the spring assembly or the support structure while 
the upper end is fixedly connected to the port end of the swivel arm. The 
extendable lock-down device is adapted to be positively locked at several 
positions near the port end of the swivel arm. 
These and other features of the present invention will become apparent with 
reference to the following detailed description of a preferred embodiment 
thereof in connection with the accompanying drawings wherein like 
reference numerals have been applied to like elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1-3 depict a preferred embodiment of the present invention. This 
embodiment contains a support structure that includes a riser flange, and 
horizontal and vertical swivel joints. An inboard (swivel) arm is attached 
to the vertical swivel joint of the support structure to enable it to move 
in horizontal and vertical planes. A spring assembly is connected to both 
the support structure and the inboard arm. One end of a lockable 
telescopic type lock-down device is pivotally attached to the spring 
assembly while the other end is fixedly attached to the inboard arm. 
Referring now to FIG. 1, this figure depicts an elevational view of a 
telescopic lock-down device connected to a spring-balanced loading arm 
when the loading arm is in the storage or idle position, i.e., when the 
loading arm is not being used for transferring material. The 
spring-balanced arms of the type shown in FIG. 1 are commonly used in the 
industry, particularly in the petroleum and chemical industry for 
transferring gasoline or liquid chemicals into trucks or tank cars. The 
spring-balanced loading arm shown here is more fully explained in U.S. 
Pat. No. 4,537,233, issued to Evart J. Vroonland et al. Another type of 
spring-balanced loading arm is shown in U.S. Pat. No. 3,244,440 issued to 
Albert A. Ashton et al. 
Still referring to FIG. 1, it shows a loading arm 100 that contains a 
support structure, a spring assembly, an inboard arm, a drop tube and a 
lock-down device. 
The support structure contains a horizontal swivel joint 12 which is 
connected to a vertical swivel joint 14 via an elbow member 15. The 
horizontal swivel joint 12 is also connected to a riser flange 10. The 
horizontal swivel joint 12 enables the support structure to rotate in a 
horizontal plane about the flange 10. 
An inboard or swivel arm 30, which has an elbow 32 at one end (the riser 
end) and another elbow 34 at the other end (the apex or the port end), is 
pivotally connected to the vertical swivel joint 14. The elbow 34 of the 
inboard arm 30 terminates into a swivel joint 40. 
A drop-tube 42 is pivotally connected to the swivel joint 40 via an elbow 
44. The arrangement described thus far enables the inboard arm to move in 
both horizontal and vertical planes and also enables the drop-tube 42 to 
move along a plane which is parallel to the plane in which lies the 
inboard arm 30. 
As shown in FIG. 3, a spring assembly or a spring support system 20 is 
connected to both the support structure and the inboard arm 30. It will be 
noted that a counterweight can easily be substituted for the spring 
assembly. When a counterweight is used to balance the loading arm, it is 
generally connected only to the inboard arm. The spring assembly 20 
includes securing means 22 adapted to support the spring assembly either 
directly on the riser (not shown) or on the support structure (shown in 
FIG. 3). The spring assembly 20 also includes a housing 28 which is 
adapted to have a coil spring therein. A spring arm cap 25 is adapted to 
close one end of the housing 28. A spring extension element 27 is attached 
to the spring and a linkage arm 24. The linkage arm 24 in turn is adapted 
to connect and be affixed to attachment means 26 for attaching the spring 
assembly 20 to the inboard arm 30. 
Thus, the loading arm of FIG. 1, wherein the inboard arm 30 is pivotally 
connected at one end (the riser end) to the support structure and at the 
other end (the port end) to a drop-tube 42, is capable of being moved and 
positioned in any desired position about the riser flange 10 both when the 
loading arm is used to transfer material and during storage. Thus, the 
loading arm 100 is capable of moving in a horizontal plane about the 
horizontal swivel joint 12 and in a vertical plane about the vertical 
swivel joint 14. Also, the drop-tube 42 is capable of moving about the 
port end of the inboard arm 30 in a plane which is parallel to the inboard 
arm. 
Loading arms of the type described thus far are used to transfer materials 
into tank trucks and tank cars. Before describing the lock-down device of 
the present invention, it is considered helpful to understand how a 
loading arm operates without the use of such a device. To transfer the 
material into a tank car or truck, the loading arm is moved to a 
horizontal position as shown in FIG. 2. In this position, the coil spring 
of the spring assembly 20 provides a counterbalance force, i.e., the 
spring force, as shown by the arrow A which is counter to the direction of 
the movement of the inboard arm. The material flow during loading is shown 
by the direction of the arrows B. Furthermore, the jet action of the 
material flow also creates a force on the inboard arm counter to the 
direction of the material flow. Because of the counterbalance spring force 
and the jet action of the liquid being discharged from the drop-tube, the 
inboard arm 30 has a tendency to rise out of the truck or tank car loading 
port during loading operations. Various devices have been employed to 
prevent the arm from rising. These devices, which include friction and 
locking devices, are used to lock the inboard arm at or near the riser. 
Such devices require the loading arm operator -- who normally operates at 
the port end of the inboard arm where the loading port of the tank car or 
truck is located -- to move from his position at the loading port to the 
riser end to engage the locking device, which is inconvenient and time 
consuming. 
The lock-down device of the present invention is an adjustable device that 
is locked in position near the port end. This device provides a positive 
lock-down of the inboard arm of the loading arm at the port end, is 
convenient to use, and is also relatively inexpensive to build. The 
lock-down device of the present invention will now be described in detail. 
Referring now to FIG. 1, the lock-down device contains an inner tube 60 
which is slidably enclosed at the port end in an outer tube 62. The inner 
tube 60 has a series of through holes 64 in the section which slides 
inside the outer tube 62. The outer tube 62 has at least one matching 
through hole 66, and a pin 68 is connected to the outer tube with a chain 
70. The pin is adapted to be inserted into the hole 66 and the holes 64 so 
as to securely lock the inner tube in relation to the outer tube at a 
desired position or length. The riser end of the inner tube 60 is 
pivotally connected to the housing 28 of the spring assembly 20 or to the 
support structure by a lug 72. It will be noted that for the purpose of 
this invention, the riser end of the inner tube may be pivotally connected 
at any convenient place near the riser end of the inboard arm 30. The port 
end 74 of the outer tube 62 is fixedly attached or fastened to the elbow 
34 of the inboard arm 30 via a lug 76. When a counterweight is used 
instead of the spring assembly, the lower end of the inner tube can easily 
be pivotally connected to the support structure. 
During storage the loading arm is usually in the position shown in FIG. 1. 
In this position the pin 68 is generally not inserted so as to allow the 
movement of the inboard arm in the vertical plane. The overlap of the 
outer tube to the inner tube is made sufficiently long so that there 
remains a telescopic action (or an overlap) between the inner and the 
outer tubes. During loading operations the inboard arm 30 is lowered above 
the loading port of the tank car or a truck and the drop tube 42 is placed 
inside the loading port. The operator, who would be operating near the 
loading port, locks the inboard arm 30 by inserting the pin 68 in the hole 
66 and a corresponding hole 64. This assures that during a loading 
operation the loading arm 100 is positively locked in the desired 
horizontal position. After the material has been transferred, the pin 68 
is disengaged and the inboard arm 30 is slowly moved to the storage or 
idle position of FIG. 1. 
FIG. 4 shows an alternate embodiment of the lock-own device of the present 
invention. This device contains a linkage arm 80, one end of which is 
pivotally connected to the spring housing 28 or to the support structure 
via a lug 88 and the other end is slidably placed into a guide member 82. 
The guide member 82 has at least one through hole 84. The linkage member 
80 has a series of holes 86 so that when the linkage member 80 slides into 
the guide member 82 the holes 86 align with the hole 84. A pin 90 is 
adapted to lock the linkage arm into the guide member at a desired 
position or length. When a counterweight is used instead of the spring 
assembly, the pivot end of the linkage arm is generally connected to the 
support structure. 
FIG. 5 shows the cross-section of the lock-down device of FIG. 4 taken 
along 5--5. Although it is not always necessary, but for structural 
support, a tee type linkage 93 was used for structural support in this 
configuration. 
Although only two embodiments of the lock-down device of the present 
invention have been described, a variety of alternative embodiments could 
be provided from the designs described herein and the invention could be 
applied to a variety of equipment and uses, particularly where there is a 
need to positively lock in position material handling systems. Various 
improvements, modifications and alternative applications and usages will 
be readily apparent to those of ordinary skill in the art. Accordingly, 
the scope of the instant invention should be considered in terms of the 
following claims and it is not to be limited to the details of the 
embodiments and the structures and operations shown in the specification 
and drawings.