Power drive mechanism for trailer landing gear

A drive motor is arranged to be secured to the frame of a manually operated trailer landing gear assembly, and a releasable coupling is provided for connection between the output shaft of the drive motor and an input shaft of a gear reduction assembly of the landing gear assembly whereby the manual drive is converted to power drive. The releasable coupling allows the drive motor to be disconnected from the gear reduction assembly in the event that it is desired to provide manual operation. The releasable coupling has a structure which maintains a drive connection through axial shifting movements of the gear reduction assembly input shaft.

BACKGROUND OF THE INVENTION 
This invention relates to a new and novel power drive mechanism for trailer 
landing gear and also pertains to a power drive mechanism arranged to 
convert a hand operated mechanism to a power mechanism. 
Semi-trailers or similar vehicles are provided with front landing gear 
arranged to support the front of the trailer on the ground for loading or 
unloading the trailer while the tractor vehicle is detached. These landing 
gears have jack-type structures so that the front of the trailer can be 
raised or lowered for connecting the trailer to or disconnecting it from 
the tractor vehicle. Most landing gears of this type employ manual means 
for operating the jack structure. The jack structures have a cross driven 
shaft, a gear reduction assembly on the driven shaft, a drive shaft 
projecting from the gear reduction assembly, and a crank for manually 
operating the drive shaft. Such manually operated jack structures are 
difficult to operate and require considerable time in their operation. 
Powered lift mechanisms having heretofore been provided for various types 
of landing gear or dolley assemblies but such power mechanisms have the 
disadvantage that the power drive thereof requires special landing gear 
constructions which are complex in structure and expensive to manufacture. 
Thus, power drives of previous power driven mechanisms are not arranged 
for adaptation to existing landing gear assemblies. In addition, such 
mechanisms do not provide the option of allowing either powered or manual 
operation whereby the landing gears are inoperative in the event of a 
failure or absence of the source of power. 
SUMMARY OF THE INVENTION 
According to the present invention and forming primary objectives thereof, 
a power drive mechanism for trailer landing gears is provided that is 
simplified in construction and that is readily adaptable to most existing 
hand driven mechanisms of trailer landing gears. Also, the power drive 
mechanism is readily detachable so that the landing gears can be manually 
operated if desired. Furthermore, the power drive mechanism is versatile 
as to application to either side of the trailer and also on either an 
inner or outer side of the landing gear. 
In carrying out the invention, a drive motor, such as an electric motor, is 
arranged for mounting on frame members of trailer landing gear and also is 
arranged so that the output shaft thereof can be axially aligned and 
coupled to a projecting input shaft of a gear reduction assembly for a 
driven shaft which has a drive connection with telescoping leg portions of 
the landing gears. Coupling means between the motor and the input shaft of 
the gear reduction assembly provide ready connection of of the drive motor 
to the gear reduction assembly and also allow shiftable operation of the 
input shaft of the gear reduction assembly. 
The invention will be better understood and additional objects and 
advantages will become apparent from the following description taken in 
connection with the accompanying drawings.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
With particular reference first to FIG. 1, the numeral 10 represents a 
front portion of a semi-trailer in common usage. Such trailers have a 
fifth wheel structure (not shown) for removable connection to a pulling 
vehicle or tractor (also not shown) and carry a landing gear assembly 12 
adjacent their front end which is used for support of this end of the 
trailer when disconnected from the tractor vehicle. 
FIGS. 1 and 2 show a typical landing gear assembly, comprising a pair of 
vertical tubular housings 14 secured together by cross frame members 16 
and securely attached to the trailer by some of such cross members and 
also by side depending frames 18. Vertical housings 14 receive telescoping 
leg members 20 through their lower ends, and such leg members have a 
conventional drive connection with the housings 14, such as a screw 
connection, forming a jack-like arrangement which can extend and retract 
the leg members. Such jack structure is not shown in detail since various 
types of conventional jack structures can be employed. 
A cross driven shaft 22 extends between the two housings 14 in a journalled 
support and has suitable drive connection with the operating jack 
mechanisms of the leg members 18 as in conventional structure. Rotation of 
the driven shaft 22 operates the jack structures in unison to raise or 
lower the leg members 20. 
The output of a gear reduction assembly 24 of conventional construction is 
connected to the shaft 22 and has an input shaft 26 projecting therefrom. 
The shaft 26 projects from both sides of the gear reduction assembly 24 
which allows such assembly to be mounted on either side of the trailer. 
One end of this shaft projects outwardly through the adjacent landing gear 
support frame 18 and normally receives a hand crank for manual operation 
of the driven shaft 22 through the gear reduction assembly 24. Each of the 
projecting ends of the shaft 26 has a diametral aperture 28, FIG. 3, 
adjacent the free end thereof which normally receives a crank attaching 
pin prior to conversion by the instant invention. Shaft 26 is shiftable 
axially in a change speed ratio of the gear reduction assembly. 
According to the invention, a drive motor housing 30 is provided in an 
arrangement such that it can be mounted on a frame member 16 of the 
landing gear assembly adjacent the gear reduction assembly 24. For this 
purpose, the drive motor has a support bracket or base 32 arranged for 
connection to one or more cross frame members 16 of the landing gear 
assembly. Such connection may comprise a bolted connection 34 as shown or 
it may comprise any other connection such as angle irons welded between 
the motor housing 30 and the frame 16 of the landing gear. 
Housing 30 encloses a motor 36 having an output shaft 38. Motor 36 
comprises an integral part of a mounting bracket 40 having a bolted 
connection 42 with the housing 30. This bracket is angular in shape, 
having a main body portion 40a which is bolted to the housing and a 
partial end portion 40b which together with an end wall 30a on the housing 
30 supports a bearing 44 in aperture means 45 in the portions 30a and 40b. 
A sleeve-type coupler 46 provides connection between the output shaft 38 of 
the motor and the shaft 26 of the gear reduction assembly 24. This coupler 
has a first open end portion 46a dimensioned and arranged to fit on the 
shaft 38. End portion 46a is coupled to the shaft 38 by one or more pins 
48, preferably two, disposed in spaced relation on the shaft and extending 
at right angles to each other. These pins are mounted in aligned apertures 
50 in the two members. 
The coupler 46 has a second open end portion 46b of reduced diameter and 
having journaled support in bearing 44. The internal diameter of sleeve 
portion 46b is of predetermined dimension so as to receive the shaft 26. 
End portion 46b includes diametrically aligned, elongated slots 52, FIGS. 
3 and 4, arranged to receive a cross pin 54 which as associated with the 
slots secures these parts rotatably together but at the same time allows a 
short slidable adjustment of such parts. 
In the installation of the present power drive on existing hand operated 
assemblies, the motor housing 30 is secured on the trailer in a selected 
position so as to align the projecting end 46a of the coupler 46 with the 
input shaft 26 of the gear reduction assembly 24 and also in selected 
spaced relation for proper attachment of the connector 46 with the shaft 
26, namely, a proper spacing of the motor housing 30 from the input shaft 
26 so as to allow shaft 26 to shift. As thusly installed, a hand operated 
landing gear assembly is converted to a power operated assembly. 
A loop-type shiftable handle 58 can be mounted on the outer projecting end 
of the shaft 26 for ease of shifting the shaft. The handle is suitably 
apertured to receive a cross pin 60 extending through such apertures and 
also extending through the existing aperture 28 that previously mounted 
the hand crank in place. 
The present structure thus provides a simplified power conversion for hand 
operated trailer landing gear, and in view of the motor structure and 
coupling means, such power drive can be readily applied to existing 
landing assemblies employing a gear reduction assembly with a projecting 
drive shaft of the type shown. The conversion to power can be accomplished 
in a short time and with minimum expense. In addition, the structure of 
the coupler 46 allows the drive attachment of the motor to be disconnected 
from the shaft 26 in the event that it is desired or necessary that hand 
operation be accomplished. For such purpose, it is merely necessary to 
remove pin 54 to disconnect the motor and to remove handle 58 for mounting 
of the hand crank. 
Operating controls 62, such as switch means in the event that the drive 
motor 30 is an electric motor, are suitably mounted for convenient 
manipulation, such as on one side of the landing gear frame 16, for 
controlling extension and retraction of the leg members 20. 
It is to be understood that the form of my invention herein shown and 
described is to be taken as a preferred example of the same and that 
various changes in the shape, size and arrangement of parts may be 
resorted to without departing from the spirit of my invention, or the 
scope of the subjoined claims. For example, the motor housing 30 can as 
well be mounted on the outer side of frame member 18 and similarly 
attached to the shaft 26.