AN IMPROVED BELT SCRAPER MOUNTING
FIELD OF THE INVENTION
The present invention in general relates to belt scrapers for its application in bulk material
handling belt conveyors and in particular, to an improved belt scraper mounting with
increased cleaning efficiency, which is easy to install and possess auto adjustment
mechanism, requires no maintenance for a long period and has reduced operational and
cleaning cost.
BACKGROUND OF THE INVENTION
Belt Scrapers are used in bulk material handling belt conveyors to avoid material carry
back, reduce spillage and keep belt clean. Clean belts help prevent material build up on
snub pulley and return rollers and increase its life, thereby reducing cleaning cost,
downtime cost and mis-tracking of the belt.
In first generation Counter weight belt scraper, single blade design is made from thick
rubber strip (wider than belt width) under the return belt and the counter weight provided
at the side of the belt scraper with a pivot point to provide contact with the belt. The initial
load exerted to the belt is approximately 80 - 90 Kgs. With time when the cleaning
effectiveness reduces, the weight is increased and it can go up to 150 Kgs.
Cleaning efficiency is approx 60-68 % and always, it is needed to increase counter weight
load on a regular basis against blade wear. It is very less effective and high maintenance is
involved.
Second generation fixed mount belt scraper's segmented blades module are made of hard
alloy steel with rubber cushion at the bottom of blade mounted on a steel tube with both
end fixed mount. It does not have automatic adjustments against blade wear. It provides
inconsistent contact pressure to the belt which is approximately 100 - 125 Kgs.
Cleaning efficiency is approx 70-85 % and always, there is need to lift-up of the fixed mount
on a regular basis against blade wear. It is less effective and high maintenance involved.
Pneumatically operated third generation belt scraper having segmented blades module are
made of hard alloy steel with or without polymer cushion at the bottom mounted of blade on
a steel tube with ratchet and pinion mount and adjustment done through compressed air at

7-10 bars pneumatically. They provide inconsistent load to the belt of approximately 90 -
110 Kgs.
Cleaning efficiency is approx 75-85 %. There is a need to pump air periodically to maintain
the blade to belt contact due to drop in air pressure / leakage / chocking of air. Maintenance
requirement is high.
In fourth generation belt scrapers with shock absorber which acts as semi automatic
adjustments to some extent but, there is a need for periodic manual adjustments against
blade wear in every 3-4 weeks interval. This type of belt scrapers have segmented type
metallic blades module with pivot point below the scraping edge mounted on a steel tube
with both ends rubber shock absorber. It provides comparatively less load to the belt, which
is approximately 24 - 80 Kgs.
Cleaning efficiency is approx 92-95 %. It provides less consistency against heavy duty, high
speed, vibration and bi-directional belt operation.
Accordingly there was a long felt need to design belt scraper mountings which are
maintenance free and long lasting and facilitates automatic adjustment in the field of bulk
material handling conveyor systems to meet the increasing belt capacity (tonnages), higher
belt speed and heavy duty of belt with wider belt conveying system.
The present invention meets the aforesaid long felt need.
All through out the specification including the claims, the words "conveyor belt", "scraper
blade" "scraper holding arm", "spring", "washer", "stud", and "nut" are to be interpreted in
the broadest sense of the respective terms and includes all similar items in the field known
by other terms, as may be clear to persons skilled in the art. Restriction / Limitation if any,
referred to the specification, is solely by way of example and understanding the present
invention.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved belt scraper
mounting which is maintenance free and provide long lasting cleaning efficiency & facilitates
automatic adjustment in the field of bulk material handling conveyor systems to meet the

increasing belt capacity (tonnages), higher belt speed and duty of belt with wider belt
conveying system.
It is another object of the present invention to provide an improved belt scraper mounting
system possessing higher efficiency of belt cleaning compared to the contemporary belt
scrapers.
It is yet another object of the present invention to provide an improved belt scraper
mounting system which provides easy and flexible installation.
It is a further object of the present invention to provide an improved belt scraper mounting
which provides auto adjustment mechanism and compensate the need of varying loads to
maintain contact with the belt.
It is a further object of the present invention an improved belt scraper mounting system
which requires absolutely no maintenance for a very long period.
It is another object of the present invention to provide an improved belt scraper mounting
system possessing reduced operational and cleaning cost.
It is another object of the present invention to provide an improved belt scraper mounting
system which possesses & confirmed precision belt cleaning.
It is yet another object of the present invention to provide an improved belt scraper
mounting system which completely eliminates sagging of scraper assembly permanently
and confirmed precision belt cleaning continuously.
It is another object of the present invention to provide an improved belt scraper for its
application in bulk material handling conveyor systems, which is equipped with automatic
scraper adjustment against blade wear and does away with the need for manual lifting of
scraper fixing mount in an upward direction towards the belt to compensate blade wear.
How the foregoing objects are achieved and the other aspects of the present invention will
be clear from the following description which is purely by way of understanding and not by
way of any sort of limitation.

SUMMARY OF THE INVENTION
Accordingly, the present invention provides an improved belt scraper mounting for belt
conveyors having conveyor frame / stringer, comprising : a scraper blade module assembly
and a means for holding said blade module assembly with said conveyor frame / stringer on
both sides of said belt scraper, said means being adapted to function in an auto adjusting
mode.
In accordance with preferred embodiments of the belt scraper mounting of the present
invention:
-said means comprises of an upper dynamic spring adjuster and a lower dynamic spring
adjuster;
-said belt scraper works in the range from 300 mm and 3200 mm of belt width and said
upper dynamic spring adjuster and said lower dynamic spring adjuster together constitute a
dynamic auto adjusting scraper fixing mount;
-said upper and lower dynamic spring adjuster are operatively adapted to be connected with
a scraper holding arm through a long stud, said blade module assembly being mounted on
said scraper holding arm and said scraper holding arm being kept in position by means of a
step washer;
-said auto adjusting mount comprises of a pair of helical springs in which said lower spring
has higher suspension stability than said upper spring;
-said dynamic auto adjusting scraper fixing mount is adapted to hold a circular tube scraper
blade module assembly;
-said dynamic auto adjusting scraper fixing mount is adapted to hold a square / rectangular
/ triangular or any other cross-section tube scraper blade module assembly;
-one helical spring is placed above said scraper holding arm and another helical spring is
placed below said scraper holding arm and are kept in position by means of washer and nut
arrangement.

DETAILED DESCRIPTION OF THE INVENTION
The following describes some preferred embodiments of the present invention, which are
purely for the sake of understanding the performance of the invention, and not by way of
any sort of limitation.
As stated before the present invention primarily aims at providing improved belt scrapers
mounting system which is maintenance free and long lasting and facilitates automatic
adjustment in the field of bulk material handling conveyor systems to meet the increasing
belt capacity (tonnages), higher belt speed and heavy duty of belt with wider belt
conveying system.
Belt Scrapers generally consist of two different major parts namely,
a) Scraper Blade module Assembly and
b) Scraper Fixing Mount.
Scraper Blade module Assembly: It is mounted on a steel tube by means of nuts and bolts
and placed under the belt to touch and clean the belt surface.
Scraper Fixing Mount: It holds the scraper blade module assembly against the belt both
sides of the tube to the conveyor stringer frame by means of nuts and bolts. Thus, there is
no automatic scraper adjustment against the blade wear hence, always need manual lifting
of scraper fixing mount upward direction towards the belt to compensate the blade wear.
In the present invention the existing scraper fixing mount is replaced by dynamic auto
adjusting mount. This feature is indispensable for the invention.
Figure 1 illustrates a perspective view of the improved belt scraper in accordance with a
preferred embodiment of the present invention. The entire belt scraper assembly wherein
the scraper blade module is in contact with the conveyor belt is provided in the said figure.
As shown in the figure the scraper holding arm (4) on which the scraper blade module (3) is
mounted and kept in position by a heavy duty upper dynamic spring adjuster (1) located
above it and another heavy duty lower dynamic spring adjuster (2) located below it.
To meet the growing market demand of maintenance free and long lasting automatic
adjustment of Belt Scraper in the field of bulk materials handling conveyor systems and to

meet the increasing belt capacity (tonnages), higher belt speed and duty of belt with wider
belt conveying system, the present invention thus provides an automatic and long lasting
vibration and maintenance free belt scraper suspension for the belt width 300 - 3200 mm.
The improved belt scraper automatic adjusting mount in the present invention, primarily
consists of:
1) Heavy Duty Upper Dynamic Spring Adjuster (1)
2) Heavy Duty Lower Dynamic Spring Adjuster (2)
3) Step Washer (5), Stud (6) and so on as described hereinafter.
The accompanying figure 2 illustrates a more detailed sectional view of the improved belt
scraper mounting showing its different components as according to a preferred embodiment
of the present invention. As shown in the figure the springs (1,2) are kept in position by a
couple of flat washers (5,5') on either side of the spring and tightened by means of a lock
nut (7,7') arrangement. The scraper holding arm is kept in position by means of a step
washer (8). The springs (1, 2) are affixed on the conveyor frame by means of a stud (6).
The figure 3 shows a circular tube scraper blade assembly, while in figure 4, the same is
square. It is to be understood that the dynamic auto adjusting scraper fixing mount of the
belt scraper mounting according to the present invention, is adapted to hold a square /
rectangular / triangular or any other cross-section tube scraper blade module assembly.
In the present invention the improved belt scraper holds the existing blade module
assembly with the conveyor frame / stringer. The dynamic spring assembly (1,2) with
scraper holding arm(4) inserted through a long stud, boost the existing scraper blade
module assembly to a new high degree of cleaning efficiency continuously while in touch
with the belt surface in suspension / floating condition, even after the scraper blades
modules gets worn-out. Thus, it delivers vibration free precision belt cleaning for a long
period without any manual adjustment/ servicing.
Design Calculations involved in said improved belt scraper as according to the present
invention with a few hypothetical parameters is illustrated as follows:
Load Calculation for 1000 mm Belt Width Scraper
(Material Specification: EN 45).

Force (F) = Load due to scraper assembly weight + Load due to belt velocity + Load due to
pressure given by the blade + Load of upper spring,
F = (F1 + F2 + F3 + F4)
F1 = (45 - 2 x 6.1) x 9.81 = 322 N.
F2 = (Power transmitted by the motor / Belt velocity) Cos60 x Cos30.
F3 = 8x5x9.81 = 393 N.
F4 = Max.1800 N (Consider as per design).
So, F = (322 + F2 + 393 + 1800) = (2515 + F2) N.
Lower Spring Calculation:
Let consider, W = Design the spring at max. load of 5000 N [for Safety Purpose].
Free Length of Spring = 130 mm.
Length at Full Load = 100 mm.
Inner Dia. of Spring = 45 mm.
Shear Stress = 8 x F x D/3.14d^3 [Allowable Shear Stress = 450 N/mm^2]
d = 10.74 mm.
Spring Index (C) = 5.18
Wahl's Correction Factor (K) = (4C-1) / (4C-4) + 0.615 / C = 1.29
Therefore, Modified Wire Dia,
Shear Stress = K x 8 x W x D/3.14d^3
d = 12 mm.
Total Deflection = 8 x W x C^3 x N / G x d [G=Modulous of Rigidity=84GPa, N=7]
= 30 mm.
Spring Constant = 5000 / 30 = 167 N / mm.
Upper Spring Calculation:
Lets consider, W = Design the spring at max. load of 2700 N [for Safety Purpose].
Free Length of Spring = 80 mm
Length at Full Load = 50 mm.
Inner Dia. of Spring = 45 mm.
Shear Stress = 8 x F x D/3.14d^3 [Allowable Shear Stress = 450 N/mm^2]
d = 8.75 mm.
Spring Index (C) = 6.14
Wahl's Correction Factor (K) = (4C-1) / (4C-4) + 0.615 / C = 1.246
Therefore, Modified Wire Dia,
Shear Stress = K x 8 x W x D/3.14d^3
d = 10 mm.

Total Deflection = 8 x W x C^3 x N / G x d [G=Modulous of Rigidity=84GPa, N=5]
= 30 mm.
Spring Constant = 2700 / 30 = 90 N / mm.
Suspension Stability of Spring for 1000 mm Belt Width Scraper:
Downward Force Given by Upper Spring (M) = 90 x 22 = 1980 N.
[Upper Spring Compression is 22 mm].
Downward Force by Belt Conveyor due to Belt Velocity=(10x10^3/3) Cos 60xCos 30
[Motor = 10 Kw, Belt Speed = 3 m/sec]
= 1445 N
Considering, Force Balance on One Side Spring. The above Force to be half of the Total
Force.
So, Downward Force by Belt Conveyor due to Belt Velocity (N) = 1445 / 2 = 722 N.
[Load of half Scraper Wt = 50 / 2 = 25 Kgs. of 1000 mm B/W]
Total Downward Force of Upper Spring (P) = (M + N + O) = (1980 + 722 + 250)
= 2952 N.
Upward Force given by Lower Spring (Q) = 167 x 14 = 2338 N + Load of Rubber
Suspension of Scraper [Wt = 125 Kgs. of 1000 mm B/W and Lower Spring Compression is
14 mm] = 2338 + 1250 = 3588 N.
Total Upward Force of Lower Spring (Q) = 3588 N.
Suspension Stability of Lower Spring = R = (Q - P) = (3588 - 2952) = 636 N.
Therefore, Percentage of Suspension Stability of Lower Spring against Upper Spring
= (Q - P) / P x 100 % = 21.54 %.
The non-limiting advantages achieved by the improved belt scraper are as follows:
1. Easy / Flexible Installation.
2. Auto Adjustment / No Maintenance for a long period (12-16 Weeks min).
3. Confirm Precision Belt Cleaning (Clean up-to 0.05-0.1 mm thin layer of carry back).
4. High Cleaning Efficiency for a long period (12-16 Weeks min).
5. Reduced Operational and Cleaning Cost.
6. Presence of automatic adjustment against blade wear does away with the need for
normal lifting of scraper fixing mount in upward direction, towards the belt to
compensate the blade module wear.

The improved belt scraper mounting is very handy and suitable for all type of belt scrapers
replacing the existing fixed mount assembly, unscrewing the nut / bolt. Also, it has an
option for circular, square ,rectangular or any other cross-section tube scraper blade module
assembly holding facilities as shown in the accompanying figures 3 and 4 respectively.
Automatic Adjustment:
As stated before, the improved belt scraper has two dynamic helical spring assemblies (1,2)
, one each is placed above and below the scraper holding arm with adjustable shoulder
nuts (7,7') can be compressed by 30 mm max. in either directions and make them stable
against belt velocity / precision belt cleaning (Shown in figures 1 and 2).
Since the lower spring having approx 20 % higher suspension stability than upper spring it
always keep the scraper blade module (3) in touch with the belt surface (10) automatically,
even after the blade module wear. Therefore, no maintenance is required for a longer
period.
Precision / High Efficiency Belt Cleaning:
The improved belt scraper cleans the belt surface further to a new high degree of precision
cleaning to remove even inherent micro fines materials and moisture from the belt surface.
Also, it prevents sagging of existing scraper assembly due to its dynamic spring assembly
design. Thus, cleaning efficiency increases up to a level of 99.5 % as shown in figure 7.
Figure 5 illustrates precision belt cleaning as performed by the improved belt scraper
mounting of the present invention. It shows a belt scraper blade module assembly fitted
with highly wear resistant tip brazed with its supporting base approximately 1mm above for
the very minimal frictional contact with the belt surface at an angle against the direction of
belt. This ensures sharp and precision cleaning of inherent carry back materials and
moisture from the micro contours of the belt surface efficiently. With the help of the
improved belt scraper mounting according to the present invention the blade module tip is
kept in position for a longer period ensuring unhindered performance for a substantially long
period of time.

Figure 6 illustrates sagging of existing belt scraper assembly. The firmed line specifies the
minor sagging of existing belt scraper assembly by approximately 3 ° two to three weeks
after initial installation. This sagging also to be prevented and firmed contact with the belt
surface always to be maintained by using dynamic spring mounting assembly. The reference
numeral (9) indicates the scraping edge initially after installation. The reference numeral
(10) indicates the belt direction.
The dynamic auto adjusting scraper fixing mount of the belt scraper mounting according to
the present invention, is adapted to hold a square / rectangular / triangular or any other
cross-section tube scraper blade module assembly;
Reduced Operational and Cleaning Cost:
In the improved belt scraper the cleaning efficiency is enhanced by 14.5 % also preventing
existing scraper assembly sagging, thereby improving productivity and reducing manpower
/ maintenance cost. Figure 7 illustrates the efficiency curve achieved by the improved belt
scraper of the present invention on trial run. It can be seen that even after eighteen weeks
of usage, the efficiency is 98%. Comparatively, on running with 2nd / 3rd generation
scrapers, after two weeks, the efficiency has been found to be 75% only as compared to the
initial efficiency of 85%. With 4th generation scrapers, after 4 weeks the efficiency has been
found to 92% from 95% initially..
All blade module assemblies can be directly mounted with the improved version of the belt
scraper according to the present invention, to achieve automatic scraper adjustments with
high belt cleaning efficiency, precision belt cleaning of 98-99.5 % for a longer period without
any maintenance thereby, highly reduced carry back, manpower, downtime and increased
productivity / reduced cost.
The present invention has been described with reference to some drawings and preferred
embodiments, purely for the sake of understanding and not by way of any limitation and the
present invention includes all legitimate developments within the scope of what has been
described hereinbefore and claimed in the appended claims.

WE CLAIM:
1. An improved belt scraper mounting for belt conveyors having conveyor frame / stringer,
comprising : a scraper blade module assembly and a means for holding said blade module
assembly with said conveyor frame / stringer on both sides of said belt scraper, said means
being adapted to function in an auto adjusting mode.
2. The improved belt scraper mounting as claimed in claim 1 wherein said means comprises
of an upper dynamic spring adjuster and a lower dynamic spring adjuster.
3. The improved belt scraper mounting as claimed in claims 1 and 2 wherein said belt
scraper works in the range from 300 mm and 3200 mm of belt width and said upper
dynamic spring adjuster and said lower dynamic spring adjuster together constitute a
dynamic auto adjusting scraper fixing mount.
4. The improved belt scraper mounting as claimed in claims 1 to 3 wherein said upper and
lower dynamic spring adjuster are operatively adapted to be connected with a scraper
holding arm through a long stud, said blade module assembly being mounted on said
scraper holding arm and said scraper holding arm being kept in position by means of a step
washer.
5. The improved belt scraper mounting as claimed in claims 3 and 4 wherein said auto
adjusting mount comprises of a pair of helical springs in which said lower spring has higher
suspension stability than said upper spring.
6. The improved belt scraper mounting as claimed in claims 1 and 3 wherein said dynamic
auto adjusting scraper fixing mount is adapted to hold a circular tube scraper blade module
assembly.
7. The improved belt scraper mounting as claimed in claims 1 and 3 wherein said dynamic
auto adjusting scraper fixing mount is adapted to hold a square / rectangular / triangular or
any other cross-section tube scraper blade module assembly.
8. The improved belt scraper mounting as claimed in claims 3, 4 and 5 wherein one helical
spring is placed above said scraper holding arm and another helical spring is placed below
said scraper holding arm and are kept in position by means of washer and nut arrangement.

9. The improved belt scraper mounting as claimed in claim 8 wherein said nut arrangement
comprises shoulder nuts adapted to be compressed by 30 mm in either direction, so as to
ensure stability against belt velocity / precision cleaning.
10. A method for applying a belt scraper mounting for bulk material handling belt conveyors
having conveyor frame / stringer, in the manner such as herein described, said belt scraper
mounting comprising: a scraper blade module assembly and a means for holding said blade
module assembly with said conveyor frame / stringer on both sides of said belt scraper, said
means being adapted to function in an auto adjusting mode.

An improved belt scraper mounting for belt conveyors having conveyor frame / stringer,
comprising : a scraper blade module assembly(3) and a means(1,2,4) for holding said blade
module assembly with said conveyor frame / stringer on both sides of said belt scraper, said
means being adapted to function in an auto adjusting mode.