US 1796994 A
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March 17, 1931. N. c. Hu'srl-:D
MAST ARM Filed Deo. 6, 1925 2 Sheets-Sheet l ,llIyIiIIIIIJIIIllIl W/ T/VESS lgemma?.
' March 17, 1931. N- C, HUSTED 1,796,994
MAST ARM Filed Dec. e.' 1923 2 sheets-sheet 2 /N VEA/Tal? adapted to support a lighting fixture.
Patented Mar. 17, 1931 PATENT OFFICE NORRIS C. HUSTED, OF NILES, OHIO MAST ARM Application led December 6, 1923. Serial No. 678,946.
My invention relates to mast arms and more particularly to that type of mast arm which is used to support a lighting fixture in spaced relation to the pole or mast on which it is mounted.
.Arms of this type usually include a boom, shaped so as to form an inclosed track-way,
and are provided with a trolley which is movable along the track-way and which is The trolley is usually held atthe outer end of the boom when in use. Means are provided for moving the trolley and the supported fixture inwardly along the track-way to the inner end of the boom adjacent the supporting pole when it is necessary to clean or renew the lighting fixture or any part thereof in order that such operation may be conveniently performed from the pole end of the boom.
An object of this invention is to construct a mast arm of the above type having an improved mechanism for moving the trolley back and forth along the track-way of the boom.
A further object is to construct a mast arm having few and simple parts which are at the same time rugged and positive in operation and which will be cheap to manufacture and simple to install.
These and other objects which will be ap` parent to those skilled in this particular art, I attain by means of my invention, one embodiment of which is shown by way of illustration in the accompanying drawings,. in l j M y v of the boom adjacent the` handle `23. The jhandle is of angular formation, as shown in which Figure 1 is a side elevation of a mast arm in place upon the supporting mast or pole, Fig. 2 is a plan view of the structure shown in Fig. 1, Fig. 3 is a vertical longitudinal section taken on the line 3 3 of Fig. 2, Fig. 4 is a vertical cross section on the line 4 4 of Fig. 2, Fig. 5 is a vertical longitudinal section on the line 5 5 of Fig. 2, Fig. 6 is a` vertical cross section on the line 6 6 of Fig. 5, showing the trolley structure, Fig. 7 is a horizontal longitudinal section. on the line 7 7 of Fig. 5, .and Fig. 8 is a view similar to Fig. 7 showing a modified form of roller tensioning means.
In the illustrated embodiment of my inventoll l have Shown7 for the purposes of illustration, a sheet metal boom 10 having an inverte-d `U-shaped cross section, the ends 11 of which are curved inwardly and upwardly to form aninclosed track-way 12. A trolley 13 is supported Within the boom andl upon the inclosed track-way by wheels .14. A lighting fixture 15 may be supported from the trolley 13 through'the medium ofahangsuitable manner and `which projects downwardly below the boomthrough the longitudinal slot formed in its lower face.
The trolley is adapted to be driven or moved along the inclosed track-way from one A The driving end of the boom to the other. mechanism includes a sprocket chain 17 which is secured .atone end to the trolleyjaxle 18 which is nearest the supporting pole. From this axle the chain passes rearwardly adjacent the track-way 12 to a ysprocket wheel 19 which is mounted on 'a rotatable shaft 20 near the inner end of the boom. The chain kpasses around the sprocket wheel 19 and o'ut- Vmedium of, driving chain 17.
Projecting lugs 24 are formed on the side Fig. A, and is loosely mounted in the perforation 25 of the shaft 20 so that when it is desired'to secure the trolley against movement the handle may be turnedso as `to fit within kthe notch forme-d by the projecting lugs 24.
This prevents rotation of the .sprocket wheel 19 andV holds the trolley against movement on the track-way. vThe handle may be prevented from falling out of V"the slotv 25 by spreading the end 26 of the handle, as shown in Fig. 1, or inany other way desired.
The idler'roller 21 is adjustable longitudinally of the boom so that the chain 17 may at all times be held taut. As illustrated, the
er 16 which is secured tothe trolley in any idler roller is rotatably mounted upon a shaft 27 which projects through slots 28 in each side of the boom. The shaft 27 is supported in aV U-shaped bracket 29 which embraces the sides of the boom adjacent the slots 28. A bolt 30 is threaded through the outer end of the bracket 29 and bears aga-inst the end face 31 of the boom. By turning down the bolt 30 the idler roller 21 may be moved outwardly of the boom and the chain 17 maintained taut. The bolt 30 and bracket 29 are locked in position through the medium of a lock nut 32.
The boom 10 may be secured to the supporting pole 33` by means of a through bolt 3% extending through a perforation 35 formed at the inner end of the boom 10 for that purpose; A brace armBG is provided to hold the boom against side sway. A stay-rod 37 is secured to an angle plate 38 fastened tothe top face of the boom at its outer end. The other end of the stay-rod may be secured to the po-le 33 in any desired manner. A staple 39 or asimilar Objectis secured to the lower passof the chain 17 and extends across the curved ends 11 of the boom 1()` so as to prevent the chain from sagging below the track-way 12, in case the tension of the chain is not sufficient. In this way the entire trolley driving means is inclosed and protectedwfrom thev elements. A
In Fig. 8 I have shown ammodilied form of rollertensioning means. lThis includes a spring 40 which is inserted between the end face 31 of the b oom and `the outer end of the bracket 29. Plates 4-1 and 4:2 are provided on the boom face 31 and the bracket, respectively, for centering the spring. The outward pressure of the spring 40 which is transmitted to the idler roller -21 by thebracket maintains the chain 17 under tension at all times.
When in normal use the trolley with its supporting fixture is held against movement at the outer end of the boom by turning the handle 23 so as to engage the notch formed by the projecting lugs 24. When it isnecessary to clean or repair the lighting fixture, this may be conveniently done from the pole end of the boom by rotating the sprocket wheel 19 throughthe medium of the handle 23 so as to move the trolley 16 inwardly along the inclosed track-way. When the repair operation is finished the trolley may be returned to its normal position by rotating the sprocket 1.9 in the reverse direction. If desired, the trolley may be secured against movement at various points along the boom by simply inserting the handle between the lugs 24 when the trolley has reached the point desired. I j
Having thus described one embodiment of my inventionjwhat Irclaim as new and desire to secure by Letters Patent is:
1. A mast arm includinga boom adapted to be mounted upon a mast 'so as to extend outwardly therefrom and formed so as to be mounted upon a mast so as to extend out* wardly therefrom and formed so as to provide an enclosed trolley way, a trolley mounted on said way within said boom, a driving mechanismV for said trolley located wholly within said boom and including a driving wheel adjacent the mastend of said boom, a shaft extending through the side of said boom for operating said wheel and locking mechanism for said shaftv including slot formi-ng lugs mounted on said boom. Y
In testimony whereof, I have hereunto subscribed my name this 4th day of December,
1923. v M v. v
NQRRISl C. HUSTED.