Portable collapsible scaffold structure

A portable collapsible scaffold structure is adapted to be supported in use upon and transported by a truck or other self-powered ground vehicle, and includes a pair of extensible ladders adapted to be mounted in use adjacent to the vehicle and coupled thereto by extensible support means for raising and lowering the ladders simultaneously, the ladders supporting between their upper ends a work platform. Extensible support posts support the ladders intermediate the ends thereof and are coupled to extensible carriage means which support the lower ends of the ladders for movement along the ground or other support surface during raising and lowering of the ladders. The entire structure is hydraulically operated and control means coupled to the ladders and the platform maintain the platform substantially horizontal during raising and lowering of the ladders. The entire scaffold structure can be readily disassembled and stored on the associated vehicle for transportation thereby.

BACKGROUND OF THE INVENTION 
The present invention relates to portable collapsible scaffold structure, 
and particularly to such structure which is adapted to be supported in use 
upon and transported by a self-powered ground vehicle. 
Vehicle-mounted extensible elevated work platforms are known in the prior 
art. One such prior art apparatus comprises a truck supporting thereon a 
swivel-mounted extensible turret arm, carrying at the distal end thereof a 
work platform in the form of a bucket, generally suitable for supporting 
one, or at most two workmen. These systems are highly maneuverable and 
generally are provided with controls at the bucket so that the supported 
workman can control his position, but the apparatus is designed for 
supporting at most two workmen in a very confined work space, which 
affords little room for equipment used by the workmen. While the apparatus 
is useful for work at a fixed point or location such as in telephone pole 
or sign repair work or in rescue work, it is unsuitable for carpentry, 
roofing, painting, brickwork or the like, where the workman must work 
along an extended work area, since the entire turret must be continually 
moved as the workman changes his position along the work area. 
Collapsible vehicle-mounted scaffold structure is also known in the prior 
art, being disclosed, for example, in the U.S. Pat. No. 2,778,694 issued 
to M. E. Mitchell on Jan. 27, 1957 and U.S. Pat. No. 3,472,337, issued to 
G. L. Atchey on Oct. 14, 1969. In both of these prior art equipments, the 
scaffolding is supported in use directly above the vehicle and, therefore, 
the apparatus is limited to those applications wherein the vehicle can be 
driven underneath the work area. The Mitchell and Atchey devices could not 
be utilized for work along the outer wall of the building because the 
scaffold platform could not be positioned in use against the wall. 
SUMMARY OF THE INVENTION 
The present invention provides a portable collapsible scaffold structure 
providing an elongated work platform suitable for supporting several 
workmen and/or a considerable amount of work equipment, and affording ease 
of movement of the workmen along an extended work site. 
It is an important feature of the present invention that the collapsible 
scaffold structure is supported in use and transported by a ground 
vehicle, but is not limited in use to work positions overlying the 
vehicle. 
More particularly, it is a feature of the present invention that there is 
provided a portable collapsible scaffold structure which is disposed in 
use on the ground adjacent to the vehicle and is coupled to the vehicle by 
driven support means for controlling the elevation of the scaffold work 
platform. 
It is another feature of this invention to provide a portable collapsible 
scaffold structure which includes a scaffold platform supported by a pair 
of spaced-apart extensible boom members mounted in use on the ground, the 
boom members providing access to the platform and being coupled to the 
associated vehicle by driven extensible support means for varying the 
position and inclination of the boom members. 
It is another feature of this invention that there is provided control 
means for maintaining the work platform substantially horizontal as the 
position and inclination of the boom members is varied. 
The foregoing features are obtained, and it is an object of this invention 
to effect these advantages by providing a portable collapsible scaffold 
structure adapted to be supported in use and transported by a self-powered 
ground vehicle, the scaffold structure comprising extensible support means 
adapted to be mounted on the associated vehicle, two spaced-apart parallel 
extensible boom members releasably attachable to the support structure for 
support thereby in an inclined use configuration with the upper ends 
thereof being spaced a substantial distance horizontally away from the 
vehicle, drive means coupled to the extensible support means for effecting 
extension and retraction thereof to change the angle of inclination of the 
boom members with respect to the ground, a work platform extending in use 
between the boom members and removably pivotally secured thereto adjacent 
to the upper ends thereof, and control means coupled to the boom members 
and to the platform and operative when the angle of inclination of the 
boom members changes to effect a corresponding change in the angle between 
the boom members and the platform for maintaining the platform 
substantially horizontal, the support means and the boom members and the 
platform and the drive means and the control means all being dimensioned 
so that when disassembled from one another they may be readily stored on 
the associated vehicle for transportation thereby. 
Further features of the invention pertain to the particular arrangement of 
the parts of the portable collapsible scaffold structure whereby the 
above-outlined and additional operating features thereof are attained. 
The invention, both as to its organization and method of operation, 
together with further objects and advantages thereof, will best be 
understood by reference to the following specification taken in connection 
with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1 of the drawings, there is illustrated a portable 
collapsible scaffold structure, generally designated by the numeral 30, 
which is constructed in accordance with the present invention, and which 
is shown disassembled and stored on a truck, generally designated by the 
numeral 20. The truck 20 has front wheels 21 and rear wheels 22 supporting 
thereon a chassis including a cab 23 and a flat bed 24. Fixedly secured to 
the truck 20 is a framework 35, including two substantially parallel 
vertically-extending front frame uprights 25, respectively fixedly secured 
to the front end of the truck 20, as on the opposite ends of the front 
bumper. Fixedly secured to each side of the bed 24 and extending upwardly 
therefrom are three longitudinally spaced-apart, substantially parallel 
rear frame uprights 27. Interconnecting the front and rear uprights 25 and 
27 along each side of the truck 20 are side rails 26 which may be 
interconnected by a plurality of transversely extending and longitudinally 
spaced-apart cross rails 28 (see FIGS. 3 and 3A). Corner braces 33 may be 
utilized to interconnect the side rails 26 and the uprights 25 and 27 to 
stiffen the frame construction. Fixedly secured to the side rails 26 and 
cross rails 28 and extending upwardly therefrom are retaining rails 29 
which define a cage for retaining the portable collapsible scaffold 
structure 30 in place when it is stored on the truck 20. Respectively 
fixedly secured to the opposite sides of the truck bed 24 and depending 
therefrom immediately behind the cab 23 are two anchor blocks 31, each 
provided with an aperture 32 therein for a purpose to be described more 
fully below. 
Respectively fixedly secured to the opposite sides of the framework 35 
adjacent to the front end thereof are two upper extensible support 
structures, each generally designated by the numeral 40. The upper 
extensible support structures 40 are identical in construction, wherefore 
only one of them will be described in detail. Each of the support 
structures 40 includes an elongated arm 41 having one end thereof 
pivotally connected as at 42 to the adjacent one of the side rails 26, and 
being provided at the other end thereof with a bracket 43. Pivotally 
connected to the bracket 43 by a pivot pin 44 is one end of an elongated 
swing link 45, to the other end of which is affixed a pillow block 46 
having an aperture 47 extending transversely therethrough. Fixedly secured 
to the arm 41 adjacent to the pivot connection 42 is a bracket 48 having 
pivotally connected thereto by a pivot pin 49 one end of a fluid-actuated 
piston rod 50, the other end of which is received in a cylinder 51 which 
is pivotally connected, as at 52, to the adjacent one of the side rails 26 
rearwardly of the pivot connection 42. It will be appreciated that as the 
piston rod 50 is extended, the arm 41 is lowered, and as the piston rod 50 
is retracted, the arm 41 is raised. 
Referring now also to FIGS. 3 and 5 of the drawings, received through the 
apertures 47 in the pillow blocks 46 is an elongated pivot brace bar 53, 
the opposite ends of which respectively extend outwardly a slight distance 
beyond the pillow blocks 46. Fixedly secured to the pivot brace bar 53 at 
spaced-apart points between the pillow blocks 46 are two coupling sleeves 
55, to which are respectively coupled the ends of two diagonal struts 54, 
the other ends of which are coupled by similar sleeves 55 to a brace bar 
56 disposed substantially parallel to the pivot brace bar 53 and 
substantially coterminous therewith. In like manner, two additional brace 
bars 57 and 58 are provided with sleeves 55 and are interconnected by a 
pair of struts 59. 
Referring now also to FIGS. 2 and 2A of the drawings, the scaffold 
structure 30 includes a pair of extension ladders, each generally 
designated by the numeral 60, and each including a lower ladder 61 and an 
upper ladder 62 disposed in overlapping sliding relationship with one 
another in standard fashion. The extension ladders 60 are respectively 
disposed in use along the opposite sides of the truck 20 extending 
forwardly therefrom. Preferably, each of the lower ladders 61 is provided 
along the inner side edge thereof with a pair of sockets 63 and 64 for 
respectively receiving therein the adjacent ends of the pivot brace bar 53 
and the brace bar 56. In like manner, each of the upper ladders 62 is 
provided along the inner side edge thereof with a pair of sockets 65 for 
respectively receiving therein the adjacent ends of the brace bars 57 and 
58. The sockets 63, 64 and 65 may include hollow rungs of the upper and 
lower ladders 61 and 62, as indicated in FIG. 3. It will be appreciated 
that any other suitable type of coupling means could be provided for 
coupling the extension ladders 60 to the brace bars 53 and 56-58. The 
pivot brace bar 53 is freely rotatable in the apertures 47 in the pillow 
blocks 46 so that the extension ladders 60 can pivot about the axis of the 
pivot brace bar 53, as will be described more fully below. 
Each of the lower ladders 61 is provided along the outer side edge thereof 
adjacent to the forward end thereof with a cable pulley 68, around which 
is wrapped a cable 67, one end of which is fixedly secured to a cable 
anchor 66 at the rear end of the upper ladder 62, and the other end of 
which is secured to a cable spool 69 affixed to the rear end of the lower 
ladder 61 (see FIGS. 2 and 2A). The cable spool 69 may be manually 
operated or motor driven for extending and retracting the upper ladder 62 
with respect to the lower ladder 61 in a well-known manner. It will be 
appreciated that, in use, the extension ladders 60 are adapted to be 
operated in tandem, the brace bars 53 and 56-58 serving to maintain a 
predetermined spaced-apart parallel and coplanar relationship between the 
extension ladders 60 at all times. 
The rear or lower ends of the lower ladders 61 are respectively coupled to 
two carriages, each generally designated by the numeral 70, which are 
identically constructed. Each of the carriages 70 includes a bracket 71 
provided with a transversely extending axle 72 on which is rotatably 
mounted a wheel 73 disposed for rolling engagement with the ground or 
other underlying support surface. The bracket 71 is also provided with a 
flange 74 to which the lower end of the adjacent one of the lower ladders 
61 is pivotally connected by a pivot pin 75. Fixedly secured to the 
bracket 71 and projecting forwardly therefrom is a cylinder 76 privided 
with a fluid-actuated piston rod 77, the forward end of which is pivotally 
connected, as at 78a, to a front bracket 78 provided with a pair of front 
wheels 79, whereby the rear end of the associated extension ladder 60 is 
supported above the ground for rolling movement therealong. Fixedly 
secured to the front bracket 78 and projecting upwardly therefrom is a 
cylinder 81 provided with a fluid-actuated piston rod 82, the upper end of 
which is pivotally connected as at 83a to an attachment bracket 83 fixedly 
secured to the outer side of the associated lower ladder 61 intermediate 
the ends thereof. 
Fixedly secured to the cylinder 81 intermediate the ends thereof is a 
coupling bracket 84 to which is connected an extensible coupling, 
generally designated by the numeral 85. The extensible coupling 85 
includes a cylinder 87, one end of which is pivotally connected to the 
coupling bracket 84 by a pivot pin 86, the cylinder 87 being provided with 
a fluid-actuated piston rod 88, the distal end of which is pivotally 
connected by a pivot pin 89 to a bracket 91 of a front extensible support 
structure, generally designated by the numeral 90. The front extensible 
support structure 90 includes an upwardly extending cylinder 92 to the 
lower end of which the bracket 91 is fixedly secured, the lower end of the 
cylinder 92 also being pivotally coupled by a pivot pin 93 to a foot 94 
which is adapted to rest upon the ground. The cylinder 92 is provided with 
a fluid-actuated piston rod 95, the upper end of which is pivotally 
coupled by a pivot pin 96 to a bracket 97 which is fixedly secured to the 
associated one of the lower ladders 61 adjacent to the forward or upper 
end thereof. 
It will be appreciated that when the extension ladders 60 are to be raised, 
this is effected by retracting piston rods 50 and extending the piston 
rods 82 and 95. As the ladders 60 are elevated, the lower ends thereof may 
be moved forwardly by movement of the forward ends of the carriages 70, 
which is accommodated by retraction of the piston rods 88. It will be 
understood that in lowering the extension ladders 60, the reverse 
procedure is used. Also, if desired, the carriages 70 may be locked in 
position by engagement of pins thereof (not shown) respectively in the 
apertures 32 of the anchor blocks 31 on the truck 20. The wheeled 
carriages 70 also permit the scaffold structure 30 to be moved while 
erected by simply retracting the piston rods 50 enough to lift the feet 94 
off the ground and then driving the truck 20 to the desired new location. 
For storage, the rear extensible support structures 80 and the front 
extensible support structures 90 may be folded back against the undersides 
of the associated extension ladders 60, this folding action being 
accommodated by retraction of the piston rods 77 and 88. Thus, the 
extension ladders 60 need not be disassembled from the associated 
extensible support structures 80 and 90 and may be stored therewith as a 
unit on the truck 20 in a folded or collapsed configuration. However, if 
desired, the extension ladders 60 may be completely disassembled from the 
extensible support structures 80 and 90 and from the carriages 70 and 
extensible couplings 85 by removal of the pivot pins 75, 78a, 83, 86, 89 
and 96. 
Referring now also to FIG. 4 of the drawings, each of the extension ladders 
60 is provided at the forward or upper end thereof with a platform support 
assembly, generally designated by the numeral 100. The platform support 
assemblies 100 are identically constructed, wherefore only one will be 
described in detail. Each of the platform support assemblies 100 includes 
a pair of laterally spaced-apart support bars 101 extending generally 
longitudinally of the associated extension ladders 60, each of the support 
bars 101 being provided midway between the ends thereof with a pivot 
bracket 102 for receiving therein one end of a pivot shaft 103 which 
interconnects the support bars 101 and pivotally couples them to the 
associated upper ladder 62. Each of the support bars 101 is provided at 
the rear end thereof with an upstanding retaining pin 104 and at the 
forward end thereof with an upstanding retaining pin 105, the pins 105 
being interconnected by a bumper bar 106 carrying bumpers 107 thereon for 
a purpose to be described more fully below. 
Referring now also to FIG. 4 of the drawings, a work platform, generally 
designated by the numeral 110, spans the platform support assemblies 101 
and is supported thereon between the front and rear retaining pins 104 and 
105. The platform 110 comprises four rectangular sections 111, 112, 113 
and 114, the sections 111 through 113 being substantially the same size 
and shape and the section 114 being somewhat shorter. Preferably, each of 
the sections 111 through 114 comprises a metal peripheral frame 
surrounding and supporting a platform which may be formed of steel mesh 
decking or the like. The sections 111 and 112 are hingedly interconnected 
as at 115 so that, when disassembled, they may be folded one atop the 
other for compact storage. When unfolded for use they are disposed in 
substantially coplanar relationship and are spaced apart a predetermined 
distance by the hinge connections 115. The sections 111 and 112 are 
provided at the outer corners thereof with sockets 116 for a purpose to be 
described more fully below, with the outer longitudinal sides of the 
sections 111 and 112 each being provided with a pair of spaced-apart hooks 
117. 
The section 113 is provided with a plurality of support flanges extending 
laterally outwardly therefrom substantially coplanar with the upper 
surface thereof. In use, the section 113 is dimensioned and arranged to 
fit between the sections 111 and 112 and be supported thereon by the 
support flanges 118. The outer longitudinal edge of the section 112 is 
also provided with a pair of spacedapart holes or apertures 119 adapted to 
respectively receive therein pins 120 projecting from one longitudinal 
edge of the section 114 for attaching the section 114 to the section 112. 
The section 114 is additionally provided at the outer corners thereof with 
sockets 121 for a purpose to be described more fully below, and at the 
inner corners thereof with attachment tabs 122 which are received in use 
between the front edge of the section 113 and the retaining pins 104, 
further to secure the section 114 to section 112 in use. 
When the sections 111 through 114 are thus assembled to form the platform 
110, the platform 110 is mounted upon the support bars 101 with the 
section 114 being disposed rearwardly and between the inner rear retaining 
pins 104 of the two platform support assemblies 100, and with the sections 
111 through 113 retained between the front and rear retaining pins 105 and 
104. The hooks 117 are adapted to be hooked beneath the inner ones of the 
support bars 101 on each of the platform support assemblies 100, securely 
to hold the platform 110 in place on the platform support assemblies 100. 
It will be understood that the bumpers 107 are adapted to engage the side 
of a building or the like against which the scaffold structure 30 might be 
used. If desired, a railing assembly 125, partially illustrated in the 
drawings, may be provided around the side and rear edges of the platform 
110 to protect workmen working thereon. The posts for such a railing 
assembly may be mounted in the sockets 116 and 121 and upon the rear pins 
104 of the platfrom support assemblies 100. Any suitable railing 
construction may be utilized for this purpose. Access to the platform 110 
is, of course, provided by the extension ladders 60. 
Also respectively coupled to the platform support assemblies 100 are 
identically-constructed platform leveling mechanisms, each generally 
designated by the numeral 130. Each of the platform leveling mechanisms 
130 includes a pair of mounting plates 126 respectively secured at the 
opposite sides of the upper end of the corresponding one of the upper 
ladders 62. Extending between the mounting plates 126 at the distal end 
thereof is a shaft 127. Respectively secured to the shaft 127 at the 
opposite ends thereof and extending downwardly therefrom are two brace 
arms 128 having a brace bar 129 extending therebetween. A fluid-actuated 
drive cylinder 131 is pivotally mounted by a pivot pin 132 to the bracket 
91, the cylinder 131 being provided with a piston rod 133 which has a 
curved upper end extending through a complementary opening in the brace 
bar 129 and fixedly secured to the shaft 127 intermediate the ends 
thereof. 
Also extending between the mounting plates 126 is a shaft 134 having 
fixedly secured thereto intermediate the ends thereof a pair of downwardly 
extending coupling arms 135, the lower ends of which are disposed on 
opposite sides of the piston rod 133 and are pivotally secured thereto by 
a pivot pin 135a. The inner end of the shaft 134 extends inwardly of the 
scaffold structure 30 beyond the adjacent mounting plate 126 and is 
fixedly secured to a bell crank lever 136, one end of which is pivotally 
secured by a pin 137 to a drive rod 138, which is in turn coupled by a 
pivot pin 139 to a bracket 139a Zat the forward end of the work platform 
110. 
In operation, as the scaffold structure 30 is raised, the work platform 110 
starts out in a position substantially parallel to the extension ladders 
60. As the extension ladders 60 are elevated, the piston rods 133 of the 
cylinders 131 are extended, thereby effecting, through the coupling arms 
135, a clockwise rotation of the shafts 134 (as viewed in FIG. 2), thereby 
rotating the bell cranks 136. As the bell cranks 136 rotate, they pull the 
drive rods 138 rearwardly, thereby pulling the front end of the work 
platform 110 downwardly to increase the angle between the work platform 
110 and the extension ladders 60 and maintain the work platform 110 in a 
substantially horizontal orientation as the extension ladders 60 are 
elevated. When the ladders 60 are lowered, the piston rods 133 are 
retracted, thereby rotating the shafts 134 in a counterclockwise direction 
as viewed in FIG. 2 and pushing the front end of the work platform 110 
upwardly to keep it in a substantially horizontal orientation. 
In order to provide additional support for the rear section 114 of the work 
platform 110, each of the platform support assemblies 130 includes a 
support bracket 140 having pivotally connected thereto at 141a one end of 
a link 141, the other end of which is pivotally connected at 141b to the 
rear section 114. Also pivotally connected at 142a to the support bracket 
140 is one end of a link 142, the other end of which is pivotally 
connected at 142b to the associated upper ladder 62. Also pivotally 
connected to the support bracket 140 at 143a is the rear end of a 
forwardly extending arm 142, the other end of which is pivotally connected 
at 143b to one end of a link 144, the other end of which is pivotally 
connected at 144a to an attachment bracket on the work platform 110. 
Pivotally connected to the arm 143 at 143c is one end of a link 145, the 
other end of which is provided with an elongated slot (not shown) in which 
is received a pin 145a connected to the rear end of the bell crank 136 
(see FIG. 3). Thus, the support bracket 140 and the arm 143 are coupled to 
the work platform 110 by the links 141 and 144 and are coupled by the link 
142 to the upper ladder 62 and by the link 145 and bell crank 136 to the 
shaft 134, for supporting the rear section 114 of the work platform 110 on 
the upper ladder 62 and the shaft 134. 
In operation, as the ladders 60 are elevated and the forward end of the 
work platform 110 is pivoted downwardly through the action of the bell 
cranks 136 in the manner described above, the support brackets 140 and 
associated linkages move via the links 145 and pins 145a to follow the 
tilting motion of the work platform 110, whereby the rear section 114 may 
be firmly supported while the angle of the work platform 110 is changing 
with respect to the extension ladders 60. The additional support provided 
by the support brackets 140 and associated linkages is necessary to insure 
against disengagement of the rear section 114 from the work platform 110 
when, for example, a workman is standing on the rear section 114. 
When the extension ladders 60 are elevated and the workmen are operating 
upon the work platform 110, the platform 110 is prevented from tipping 
forwardly as workmen walk along the forward edge thereof by reason of the 
piston rods 133 which are supported by the pressure in the cylinders 131. 
In order to prevent the work platform 110 from tipping rearwardly in use, 
there is provided at each end thereof a latch mechanism, the latch 
mechanisms being identical in construction, whereby only one will be 
described in detail. 
Referring in particular to FIG. 2 of the drawings, each latch mechanism 
includes a support arm 146 which is pivotally connected to the outer end 
of the shaft 134, the arm 146 extending rearwardly to a distal end which 
is received between a pair of upwardly extending arms 147, and is 
pivotally coupled thereto by a pin 146a. The upper ends of the arms 147 
are pivotally coupled to the pivot pin 144a on the work platform 110. 
Extending between the arms 147 intermediate the ends thereof is a pin 148. 
The spaced-apart arms 147 define a slot in which is received a ratchet arm 
149 overlying the pin 148 and having a plurality of ratchet teeth 
engageable therewith, the ratchet arm 149 being pivotally connected to the 
shaft 103. Also anchored on the shaft 103 is a torsion spring 149a which 
is disposed in engagement with the upper end of the ratchet arm 149 for 
resiliently urging it downwardly into engagement with the pin 148. 
The ratchet teeth are so arranged as to permit counterclockwise rotation of 
the work platform 110 about the axis of the shaft 103 (as viewed in FIG. 
2), but to prevent clockwise rotation thereof. Thus, the latch mechanism 
permits the downward tilting of the front end of the work platform 110 
during the raising of the scaffold structure 30, but prevents such tipping 
movement when the scaffold structure 30 is stationary. When the extension 
ladders 60 are to be lowered, the necessary clockwise rotation of the work 
platform 110 is accommodated by reason of the pivotal connections of the 
arms 146 and 147, whereby as the rear end of the work platform 110 tends 
to move downwardly, the ratchet pins 148 move downwardly with it, so that 
relative ratcheting movement of the ratchet arms 149 with respect to the 
pins 148 is not necessary. 
It will be understood that the platform leveling mechanism 130 described 
above is provided in connection with each of the extension ladders 60, so 
that there are two identically constructed platform leveling mechanisms 
130 respectively provided at the opposite ends of the work platform 110. 
By reason of these mechanisms 130, it is possible to maintain the work 
platform 110 in a substantially horizontal position as the scaffold 
structure 30 is erected and lowered, while at the same time providing firm 
support for the entire work platform 110, including the rear section 114 
thereof, and while the latch mechanisms effectively lock the work platform 
110 against pivotal movement with respect to the extension ladder 60 when 
the scaffold structure 30 has been erected. 
Referring now to FIGS. 2, 2A and 3A of the drawings, the cylinders 51, 76, 
81, 87, 92 and 131 are all preferably hydraulically operated, for which 
purpose there is provided a hydraulic system, generally designated by the 
numeral 150, mounted upon the truck bed 24. The hydraulic system includes 
an electric storage battery 151 which is connected through a switch 153 to 
an electric motor 152 which drives a pump 154. The pump 154 is coupled to 
a fluid control valve 155 having "Lower" and "Raise" conditions, 
respectively designated by letters "L" and "R" in FIG. 3A of the drawings. 
The control valve 155 is coupled to a conduit network including a "Raise" 
conduit 156 and a "Lower" conduit 157, the "Raise" conduit 156 being 
connected in parallel to the lower ends of each of the cylinders 51, 76, 
81, 87, 92 and 131, and the "Lower" conduit 157 being connected in 
parallel to the upper ends of each of those cylinders, for extension and 
retraction of the piston rods in a well-known manner. As is indicated in 
FIG. 2, the sections of the conduits 156 and 157 extending between 
adjacent ones of the cylinders have sufficient length to accommodate full 
extension and retraction of the associated piston rods. It will be 
appreciated that a pneumatic system could be utilized in lieu of the 
hydraulic system 150. 
The assembly and operation of the portable collapsible scaffold structure 
30 will now be described in detail. If the carriages 70, extensible 
support structures 80 and 90 and extensible couplings 85 are stored on the 
truck 20 separately from the extension ladders 60, the first step is 
reassembly of these components and placement of the extension ladders 60 
respectively along the opposite sides of the truck 20. The pivot brace bar 
53 may be permanently coupled to the pillow blocks 46, but if not, it is 
at this time assembled thereto. Also, the struts 54, sleeves 55 and the 
brace bar 56 may all be preassembled to the pivot brace bar 53, but if 
not, they are now assembled to the configuration illustrated in the 
drawings. In like manner, the brace bars 57 and 58 are assembled together 
with the struts 59. Then, adjacent ends of the brace bars 53 and 56-58 are 
inserted in the corresponding sockets in one of the extension ladders 60. 
Then the other of the extension ladders 60 is assembled to the brace bars 
53 and 56-58. Next, the platform 110 is assembled and mounted in place on 
the platform support assemblies 100. 
When the parts of the scaffold structure 30 have been thus assembled, the 
structure is erected by operation of the hydraulic system 150. Initially, 
the cylinders 76, 81, 87, 92 and 131 are folded flat against the bottoms 
of the ladders 60. Preferably, all of these cylinders are operated 
substantially simultaneously with the cylinders 51 to unfold the former 
cylinders as the ladders 60 are elevated. Thus, the piston rods 77 and 88 
are extended to unfold the rear and front extensible support structures 80 
and 90. The extension of the piston rods 95 and 133 is preferably such 
that the feet 94 remain off the ground until the scaffold structure 30 has 
been elevated to the desired height, at which time the feet 94 are lowered 
to firmly support the scaffold structure 30 on the ground. By this 
procedure, the truck 20 can be moved if necessary during the erection 
process to achieve the desired positioning of the work platform 110. As 
the extension ladders 60 are elevated to the desired angle of inclination, 
the upper ladders 62 are extended with respect to the lower ladders 61 by 
means of the cables 67, as necessary, to reach the desired height. The 
carriages 70 may move along the ground to bring the platform 110 into the 
desired operating position, for example, with the bumpers 107 in contact 
with the side of a building or the like, this movement being accommodated 
by retraction of the piston rods 88. 
It will be appreciated that the platform leveling mechanisms 130 serve to 
maintain the platform 110 in a substantially level, horizontal position 
during raising and lowering of the extension ladders 60. It will also be 
appreciated that, if desired, a control valve for the hydraulic system 150 
could be mounted on the platform 110 so that the workmen thereon could 
adjust the position of the platform 110 without having to descend 
therefrom. It will further be understood that each of the cylinders 51, 
76, 81, 87, 92 and 131 is preferably provided with its own control valve 
so that each of these cylinders can be independently controlled. 
It is a significant advantage of the present invention that the portable 
collapsible scaffold structure 30 is supported in use upon the ground 
adjacent to the truck 20, so that it may be positioned forwardly of the 
truck 20, and it is not necessary for the truck 20 to be able to drive 
immediately beneath or closely alongside the work area. Thus, the present 
invention is uniquely suitable for work along walls or the sides of 
buildings or the like for painting, siding, brickwork, carpentry, roofing, 
or the like which normally requires the use of scaffolding. 
When the work is finished, the scaffold structure 30 can be collapsed and, 
if desired, disassembled so that it can be stored in a very compact space 
on the truck 20. The erection and disassembly of the scaffold structure 30 
is readily accomplished and can easily be done by one man in less than 
half an hour. It will be understood that, while the scaffold structure 30 
has been disclosed as mountable adjacent to the front end of the truck 20, 
the apparatus could as well be set up for erection at the rear end of the 
truck 20 by appropriate modification of the placement of the upper 
extensible support structures 40. 
From the foregoing, it can be seen that there has been provided an improved 
portable collapsible scaffold structure which can be collapsed and 
disassembled for storage in a compact area on a vehicle and which can be 
simply and easily assembled and erected for use. 
There has also been provided an improved scaffold structure of the 
character described, which permits an elongated work platform to be 
automatically raised or lowered and positioned at a work site, the 
scaffold structure being disposed for use adjacent to but not immediately 
above the associated vehicle, so that it is not necessary to drive the 
vehicle beneath or immediately alongside the work site. 
There has also been provided a scaffold structure of the character 
described, which is fully and automatically adjustable, and wherein the 
work platform may be maintained level during raising and lowering of the 
scaffold structure. 
While there has been described what is at present considered to be the 
preferred embodiment of the invention, it will be understood that various 
modifications may be made therein, and it is intended to cover in the 
appended claims all such modifications as fall within the true spirit and 
scope of the invention.