The document provides information on Osborn apron feeders, including their types, widths, capacities, and lengths. It describes the key components of apron feeders such as the frame, flights, rollers, drives, and chains. It emphasizes the importance of hopper design for efficient feeding onto the apron feeder. The document includes an application data sheet to collect information needed for properly sizing an apron feeder.

1. Apron Feeders

2. Osborn Range
Introduction to Apron Feeders
Type Widths Capacities TPH
D4 900 – 2100 mm up to 1500
D6 1200 – 2400 mm up to 2000
D7 1500 – 3000 mm up to 2500
D8 1500 – 3000 mm up to 2500
D9 2000 – 3500 mm up to 5000
Lengths vary from 3 000 mm - 19 000 mm or more depending on design. The capacities shown are based on a material mass of
1.6 tonnes per cubic meter and are indicative only. Upon receipt of all the material characteristics and design parameters, Osborn
would be able to provide a more exact capacity for the selected Apron Feeder.
2
Lengths vary from 3 000 mm - 19 000 mm or more depending on design. The capacities shown are based on a material mass of
Feed Capacity
Burden Depth
(mm)
Chain Speed (m/min)
Pan Width (mm)
900 1050 1250 1500 1800 2100 2400 3000 3500
Inside skirts (mm)
800 950 1150 1400 1700 2000 2300 2900 3400
m³/h m³/h m³/h m³/h m³/h m³/h m³/h m³/h m³/h
1000
4 192 228 276 336 408 480 552 696 816
6 288 342 414 504 612 720 828 1044 1224
8 384 456 552 672 816 960 1104 1392 1632
10 480 570 690 840 1020 1200 1380 1740 2040
Note: Machines with heavier duty chains can be designed and built to suit specific duty requirements
Osborn Apron Feeders provide reliable means of controlling the feed rate to prevent surge loads to the Primary Crusher or
other plant equipment.
An Apron Feeder is run at very low speeds and at a controlled feed rate as it absorbs the impact loads of the material falling
from a dump truck or a front-end loader and is ideal for withdrawing material from under a stockpile or from under a Primary
Crusher.
Apron Feeders are of rugged, heavy duty construction and designed to handle feed sizes of up to 1500 mm and where no fines
removal is required or where fines are removed by a separate Vibrating Grizzly. When the feed material is wet, sticky or clay like,
and where other feeding equipment cannot handle it, the Apron Feeder is the machine to select. Generally, the Apron Feeder
can be installed in a horizontal or inclined position (up to 15°)depending on space limitations.
Drives can be electromechanical or hydraulic. The manganese flights are designed to overlap so as to reduce spillage. Osborn
Apron Feeders range in sizes from 900 mm wide to 3500 mm wide and are constructed using traditional D4, D6, D7 and D9
track components.

3. 3
It is very important to ensure that the loading hopper or bin is designed to achieve the most efficient feed onto the
Apron Feeder.
The machine often has to cope with high loads at start-up and reduced loads whilst running, hence load distribution via
the correctly designed hopper needs to be optimised.
Ideally, the dumping of material into the hopper needs to be controlled so that the impact of the new load is absorbed by
the last of the material from the previous load. The dumping of material into an empty hopper should be discouraged.
If it becomes impossible to dump onto a bed of material, then the load should be tipped towards the tail end of the
hopper so that the greater portion of the impact is borne by the sloping rear wall or drop box.
This method would be beneficial if the bed of material on the sloping wall comes to rest on the Apron Feeder flights in
such a position that it forms a bed for the succeeding portion of the load which is discharged from a greater height.
SIZING AN APRON FEEDER
The data sheet on the rear of this brochure, illustrates the information that Osborn requires to correctly size the Apron
Feeder. Of significant importance on any Apron Feeder installation is the design of the bin or hopper which will be used
to feed the machine.
To enable Osborn engineers to calculate the optimum size Apron Feeder, also taken into consideration as well as the
completed data sheet are the following points that we insert into our formulae:
• Flights and chain mass
• Start-up and running torque
• Chain factor of safety
- Start-up conditions – 5:1 minimum
- Running conditions – greater than 7.5:1
For Drive sizing we calculate:
• Breakaway torque
• Running torque
• Absorbed power
• Installed power
• Head shaft speed.
• Chain pull (taking material shear resistance, installation inclination resistance etc, into consideration)
Osborn generally works on twice the maximum lump size feed to be the minimum width of the Apron Feeder pan as an
indicator. Grading analysis is important for correct sizing of feeder width.
Apron Feeder with built in
Dribble or Fines Belt.
Leave at least 4 -5 flights or 800 mm
(minimum) clearance at tail shaft for
maintenance.
Loading Hopper / Bin

4. FRAME
Full length beams manufactured from
rolledsteeljoistsformthetopandbottom
members of this one piece unit. Cross
members tie the framework together
for maximum strength. Bolted onto
these crossmembers are the universal
beams which carry the impact rails and
the carrier rolls. For ease of removing
the carrier rolls, the outside carrier roll
channels are sectionalized and bolted to
the cross beams.
HEAD DRIVE SHAFT
This heavy duty shaft is machined from high grade hot rolled
steel. Each end of the shaft is machined for a drive unit, even
on installations with a single drive specification. This can have
either a left-hand or right-hand driven orientation and will
assist should one side of the shaft be damaged.
DRIVE SPROCKETS
The sprockets are of the bolt on segmental type made from wear resisting alloy
steel. They are designed with an odd number of teeth which increases the life of the
sprocket, because contact with the teeth is only completed after two revolutions.
The sprockets are bolted onto keyed on hubs.
TAIL TRACTION WHEELS
Cast steel traction wheels are lighter duty as they act purely as a directional guide
to centralise the track. Long service life can be expected as there is minimal load
carried on the traction wheels.
FLIGHTS
Cast steel flights ( or pans ) are fitted as standard and reinforced with
longitudinal packers which run in close proximity to the impact rails thus
preventing excessive loads being taken by the carry rollers. Manganese
flights are available as an option. All flight sets are individually machined
to ensure the optimum overlap of each flight is obtained to minimise
leakage. The flights are bolted to the track chain using high tensile
grade bolts.
4

5. IMPACT RAILS
These full length heavy duty steel rails are fitted to the
frame to prevent permanent distortion of the flights under
severe impact loading. Ample clearance is provided to
ensure that the flights do not drag on the rail.
BEARINGS
Anti-friction spherical roller bearings are fitted to the head and tail shafts and
housed in heavy duty plummer blocks. Bearings are grease lubricated and a
grease reservoir is included in the design of the bearing housings and end
caps. The Apron Feeder has a remote mounted electrically operated automatic
greasing system as standard.
CARRYING ROLLERS
The carrying rollers are standard tractor type featuring a hardened and
ground shaft fitted with a centre thrust shoulder and hardened roller. The
sleeve bearings on the carrying roller takes high impact loads and, with
the duo-clone seals providing lifetime lubrication an extended wear life can
be assured. Closely spaced along the length of the Feeder, smooth travel
of deck during operation is maintained.
RETURN ROLLERS
The return rollers on the Apron Feeder are steel rollers with bearing
sleeves to support the deck on its return. The rollers are mounted on a
stub shaft that is fabricated onto a plate and bolted to the lower joist.
CHAIN
Crawler tractor type track chains, sealed and lubricated, are
used on all Osborn Apron Feeders. The pins and bushes are all
made from heat treated alloy steel and hardened on the wearing
surfaces. The chain links are drop forged for increased carrying
capacity and strength. The chains can be adjusted by means
of a threaded screwed take-up arrangement. Hydraulic ram
adjustment is available as an option.
Removable stub shaft plate.
5

6. Osborn Apron Feeder Sectional View
SECTIONAL VIEW THROUGH OSBORN APRON FEEDER
As an optional extra, the Osborn Apron Feeders can incorporate a Dribble or Fines
Conveyor which is located under the feeder to catch the small pieces, fines and
lumps of material that became trapped on the feed side of the apron flights and
dribble out on the return side. This feature eliminates manual clean up and saves
on man hours.
The Dribble or Fines Belt conveys this material into a discharge chute. To protect
the Apron Feeder return rolls from material build-up caused by spillage over the
edges of the apron flights, angle iron deflectors are fitted. The use of impact rails
and rail supports are generally determined by the width of the Apron Feeder and
range from one to three or more as the width and duties increase.
6
Pan
Chain
Roller Support Beam
Main Beam
Cross Member
Return Roller
Protector
Support Roller
Return Roller
Feeder Skirt
Idler Rolls
Dribble or Fines
Conveyor Frame
Return Rolls
STD
Apron
Feeder
Optional
Scraper
Belt
Impact Rail
Impact Rail Support
EFFECTIVE WIDTH
Clearance

7. 7
Application Data Sheet - Osborn Apron Feeder
Customer Contact Person
Phone No./Email Phone No./Email
Fax.No Enquiry No.
Date of Enquiry Tender No.
SITE CONDITIONS
Location
Altitude Metres
Operating Temp. Min °C
Operating Temp. Max. °C
MATERIAL
Type
Loose Bulk Density Kg/M³
Angle of Repose Degrees
Compressive Strength Mpa
Abrasiveness High Medium Low
Moisture Content % Max % Min
Flowability Free Average Sticky
Shape of Material
DUTY
Design Capacity Top speed tph Bottom speed tph
Max.Feed Lump Size mm
Running hours per day hours
Drive selection type Hydraulic Electromechanical
Rate control Fixed Variable
Variable feed rate 60-100% 0-100%
BIN GEOMETRY
A) Hopper Wall Angle Deg
B) Hopper Length mm
C) Hopper Height mm
D) Hopper Skirt Height mm
E) Bin Height mm
F) Bin Length (Calculated) mm
G) Burden Depth mm
H) Skirt Length mm
J) Inside Skirt Width mm
K) Rear Projection mm
L) Feeder Inclination Deg
M) Rear Wall Angle Deg
Bin Volume m³
Bin Capacity tonnes
HANDING (View from tail end)
Left hand
Right Hand
SPECIAL CONDITIONS
NOTE
Minimum feeder length should be 1.5 x larger than lumpsize (width or height)
Feeder width = 2 x maximum lump size - if high % of max lumps
Burden depth = 2 x maximum lump size

8. Head Office:
PO Box 8182
Elandsfontein, 1406
Johannesburg
South Africa
Tel: +27 11 820 7600
Fax: +27 11 388 1136
Call Centre: 0861 OSBORN
E-mail: osborn@osborn.co.za
www.osborn.co.za
Companies of the Astec Aggregate and Mining Group
www.osborn.co.za www.telsmith.com www.rockbreaker.com www.astrcmobilescreens.com www.kpijci.com
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ApronFeeder/0812/Rev2