Chain stripper devices and assemblies for mining machines

A machine frame for a scraper-chain conveyor employs a housing or `plough box` containing a chain wheel for driving a haulage chain. A stripper device is provided in the housing to separate the chain from the chain wheel. The stripper device is composed of a one-piece shaped element with an arcuate blade projecting into the chain wheel. The element is fitted to a mounting flange of the housing with a single upstanding bolt-and-nut and a separate complementary locking member. The element, the locking member and the flange have shape-locking interengaging projections and recesses. The device can be positionally inverted.

BACKGROUND TO THE INVENTION 
The present invention relates in general to assemblies for use with machine 
frames of scraper-chain conveyors and more particularly to assemblies and 
arrangements which employ chain stripper devices for separating a chain 
from a chain wheel or sprocket. 
In underground mineral mining installations, it is known to employ a frame 
at one end of a scraper-chain conveyor which supports drive means driving 
the scraper-chain assembly as well as a chain used to haul a winning 
machine such as a plough along the mineral face. The machine drive chain 
is usually entrained around a chain or sprocket wheel disposed in a 
housing called a `plough box` at one side of the frame. In order to ensure 
that the chain is separated from the chain wheel, it is known to use a 
stripper device which has a blade or tongue of arcuate shape which 
projects into the peripheral profile of the chain wheel. The stripper 
device is detachably mounted within the plough box. Similar stripper 
devices can also be employed to separate the scraper-chain assembly from 
its drive drum. 
The plough box itself is quite narrow and this presents problems in fitting 
and dismantling the chain stripper device. It is known to use a two-part 
stripper device which is fitted to a horizontal wall in the plough box by 
means of bolts. An example of such an arrangement is described in U.S. 
Pat. No. 3,871,513 (Georg et. al) granted 18, Mar. 1975. Another problem 
encountered in these assemblies is that of compatability. Chain wheels of 
various sizes are used and the chain wheels are interchanged and replaced 
from time to time. Hence, stripper devices of corresponding dimensions 
need to be provided. It is also common to provide main and auxiliary drive 
stations for the conveyor and the plough box can be optionally arranged at 
one or other of the associated machine frames at the ends of the conveyor 
with the chain direction reversed. To provide for this the stripper device 
and its mounting arrangement needs to be appropriately symmetrical. 
A general object of the present invention is to provide an improved chain 
stripper device and associated plough box assembly. 
SUMMARY OF THE INVENTION 
A chain stripper device constructed in accordance with the invention is 
composed of a one-piece element provided with an arcuate blade for 
separating a chain from a chain wheel which is supported or clamped to a 
mounting flange of the plough box with the aid of a locking member with 
which the element is connected in shape-locking manner. Conveniently, the 
element and the locking member have one or more interengaging projections 
and recesses and are disposed at opposite upper and lower surfaces of the 
mounting flange. Further mating projections and recesses can be provided 
between the element and the mounting flange and/ or an adjacent structural 
wall of the plough box. The assembly can be releasably secured with the 
aid of a single nut-and-bolt extending through aligned upstanding bores in 
the element, the locking member and the mounting flange. 
The element can be provided with an extension which projects away from its 
arcuate tongue or blade and which locates on the mounting flange in a 
position opposed to the locking member. This can then provide a 
symmetrical construction permitting the element to be inverted and used 
either above or below the mounting flange. By providing appropriate 
mounting flanges on both sides of the chain wheel the stripper device can 
be located in two further alternative positions to cope with use at a main 
or auxiliary drive station. The locking member is small in relation to the 
main one-piece element and this permits the locking member to be easily 
inserted into and withdrawn from the plough box thereby to facilitate the 
fitting and dismantling operations. 
The stripper device and assembly is particularly compact and robust. The 
device can be easily dismantled and assembled even in the narrow plough 
box. The single bolt need not take up operational forces since these are 
transmitted through the shape-locking components to the plough box itself. 
The projection(s) and recess(es) between the main element and the smaller 
locking member can inhibit horizontal displacement of the main element 
while the remaining projections and recesses between the main element and 
the mounting flange and wall of the plough box inhibit vertical 
displacement. Conveniently, the mounting flange has a recess at its end 
facing the chain wheel and this recess, which receives a projection of the 
main element, is disposed on a central longitudinal plane of the plough 
box aligned with the centre of the chain wheel. The extension of the main 
element may have a projection which engages optionally in one of two 
recesses symmetrically arranged in relation to the aforesaid plane in, for 
example, a transverse wall of the plough box adjoining the flange. 
The side faces of the main element may have threaded bores therein 
permitting a filler piece to be attached thereto to close off any gap 
between the element and the inside of the plough box side walls. This is 
especially useful where chain wheels of smaller dimensions are utilized 
and where there would otherwise be some danger that the chain could become 
untensioned and jam itself between the main element and one of the plough 
box side walls. 
The invention may be understood more readily, and various other features of 
the invention may become apparent, from consideration of the following 
description. 
BRIEF DESCRIPTION OF DRAWINGS 
An embodiment of the invention will now be described, by way of example 
only, with reference to the accompanying drawings, wherein:

DESCRIPTION OF PREFERRED EMBODIMENT 
In FIGS. 1 and 2 of the accompanying drawings, a sprocket or chain wheel 10 
is disposed within a housing forming the so-called plough box represented 
schematically by chain-dotted lines 11. The plough box 11 may be 
constructed as described in U.S. Pat. No. 3,871,513. The plough box 11 
itself is fitted by means of a flanged connection to the side of machine 
frame for a scraper-chain conveyor as is known per se. The chain wheel 10 
serves to propel the drive chain of a mineral winning machine, such as a 
plough, guided for movement back and forth along the conveyor. The wheel 
10 is carried on a driven shaft 12 which extends through an opening in the 
inner side wall of the plough box 11. 
As is known per se, the chain wheel 10 has a peripheral shape corresponding 
to that of the oval links of the chain represented schematically in FIG. 2 
by chain-dotted lines 13. 
A chain stripper device 15 is mounted in the plough box 11. The device 15 
employs a one-piece element 16 formed with an arcuate blade 17 which 
extends into the groove 14 of the chain wheel 10 in order to separate the 
chain 13 from the wheel 10 in known manner. 
The element 16 is detachably secured to a flange 18 of a wall extending 
transversally of the plough box 11. As shown in FIGS. 3 and 4, the flange 
18 has a central horizontal plane passing through the centre of the chain 
wheel 10. The element 16 is provided with an integral extension 20 which 
projects over the upper surface of the flange 18. The extension 20 is 
provided with a recess 22 in its upper surface which communicates with a 
vertical bore 21. This bore 21 aligns with a corresponding bore 24 in the 
flange 18 and receives the shank of a bolt 19 used to secure the element 
16 to the flange 18. A nut 23 engages on the threaded end region of the 
bolt 19 and is received in the recess 22. A central recess 26 is provided 
in the front end face 25 of the flange 18 facing the chain wheel 10 and 
this recess 26 receives a projection 27 formed on the element 16 beneath 
the extension 20. 
As shown in FIG. 3 the rear portion of the flange 18 remote from the chain 
wheel 10 adjoins an integral wall, which forms a structural part of the 
plough box 11. The wall is of increased thickness relative to the flange 
18. 
The resultant upper and lower shoulders 38 between the flange 18 and the 
wall are provided with recesses 28. The extension 20 has a projection 29 
which engages in the upper recess 28. The provision of the interengaging 
recesses and projections 26, 27 and 28, 29 acts to locate the element 16 
positively with respect to the mounting flange 18 and resists tilting or 
vertical motion, e.g. lifting of the element 16. 
A separate locking member or piece 30 locates beneath the flange 18. The 
locking piece 30 has a rear face which engages on the shoulder 38 between 
the wall and the flange 18. The locking piece 30 has a recess 31 which 
communicates with a bore 32 aligned with the bore 24 in the flange 18. The 
recess 31 receives the head 27 of the bolt 19. The locking piece 30 is 
also provided with a stepped portion on its upper face remote from the 
recess 31 forming a recess 33 and a projection 34. The element 16 has a 
similarly shaped region providing a projection 36 and a recess 35. The 
interengagement between the respective projections and recesses 34, 35 and 
33, 36 connects the locking piece 30 and the element 16 and resists 
horizontal movement of the element 16. 
The stripper device 15 and the overall assembly as described is able to be 
used with various chain wheels 10 and in some applications an additional 
component in the form of a filler piece 41 shown in the drawings can be 
fitted as described hereinafter. When the stripper device 15 is to be 
installed the locking piece 30 is assembled to the bolt 19 and these 
components are then fitted to the underside of the flange 18 so that the 
bolt 19 projects partly into the bore 24. 
The element 16 is then placed in position onto the flange 18 and adjustment 
is made to engage the projections 27, 29 in the recesses 26, 28 and to 
align the bore 21 with the bores 24, 32. The bolt 19 is then pushed 
upwardly until the nut 23 can be engaged and tightened. Although the bolt 
19 and its nut 23 secure the components of the assembly together, forces 
which are applied to the stripper device 15 during use are taken up by the 
shape-locking arrangement represented by the interengaging projections and 
recesses and transmitted to the plough box 11. In order to dismantle the 
stripper device 15, the nut 23 is simply removed, thus, permitting the 
removal of the element 16, the bolt 19 and the locking piece 30. 
The provision of the two recesses 28, as described or otherwise, and the 
symmetrical nature of the arrangement permits the element 16 to be 
inverted and installed above or below the flange 18. By providing a 
similar flange and transverse wall structure at the other side of the 
chain wheel 10, i.e. at the left-hand side of FIGS. 1 and 2, the stripper 
device 15 can be optionally positioned at one or other side of the chain 
wheel 10 depending on the direction of the chain 13. 
As shown in FIGS. 1 and 4, the element 16 is offset laterally from the 
centre of the plough box 11 to engage in the groove 14. This means there 
is a gap of greater width between one side 39 of the element 16 and the 
inner face of the adjacent side wall of the plough box 11. A filler piece 
41 is detachably secured to the element 16 to compensate for this gap. 
More particularly, both sides of the element 16 are provided with threaded 
bores 40 so that the filler piece 41 can be secured to one or other side 
of the element 16 with the aid of screws 42. This is of particular benefit 
where chain wheels of smaller size are employed since the filler piece 41 
can reliably prevent jamming of the chain in the gap between the element 
16 and the more distant plough box side wall. As shown in FIG. 3, the 
filler piece 41 is provided with bead-like protruberances 43 which are 
symmetrical relative to the central longitudinal plane through the plough 
box 11. This enables the filler piece 41 to be inverted and used at either 
side of the element 16. The protruberances 43 assist in guiding the chain 
and preventing jamming. Where chain wheels of greater size are employed, 
the filler piece 41 can be removed.