03 Apron Feeder

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Apron Feeders



Osborn Range

Introduction to Apron Feeders

Type Widths Capacities TPH

D4 900 – 2100mm up to 1500

D6 1200 – 2400mm up to 2000

D7 1500 – 3000mm up to 2500

D8 1500 – 3000mm up to 2500

D9 2000 – 3500mm up to 5000

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 fromunder a Primary Crusher.

Apron Feeders are of rugged, heavy duty construction and designed to handle feed sizes of up to 1500mm 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 can-not 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 900mm wide to 3500mm wide and are constructed using traditional

D4,D6, D7 and D9 track components.

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

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 163210 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



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 FEEDERThe 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 than7.5:1

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 work 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 inscraper belt.

Leave at least 4 -5 flights or 800mm

(minimum) clearance at tail shaft for

maintenance.

Loading Hopper / Bin



FRAMEFull length beams manufactured from

rolled steel joists form the top and

bottom members of this one piece

unit. Crossmembers 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 SHAFTThis 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. Should one

end of the shaft get damaged, the shaft is handable and the

other end could be used.

DRIVE SPROCKETS

The sprockets are of the bolt on segmental type made from wear resisting alloysteel. 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 revolu-

tions. The sprockets are bolted onto keyed on hubs.

TAIL TRACTION WHEELSCast 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.

FLIGHTSCast 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 areindividually 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.

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IMPACT RAILSThese 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.

BEARINGSAnti-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 oper-

ated automatic greasing system as standard.

CARRYING ROLLERS

The carrying rollers are standard tractor type featuring a hardenedand 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 ROLLERSThe 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.

CHAINCrawler 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 increasedcarrying 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



Osborn Apron Feeder Sectional View

SECTIONAL VIEW THROUGH OSBORN APRON FEEDERAs an optional extra, the Osborn Apron Feeders can incorporate a Dribble

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 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 RollerProtector

Support Roller

Return Roller

Feeder Skirt

Idler Rolls

Dribble ConveyorFrame

Return Rolls

STD ApronFeeder

OptionalScraperBelt

Impact Rail

Impact Rail Support

EFFECTIVE WIDTH

Clearance



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

Ref No. AF/11/Rev1NOTEMinimum 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



Head Office:

PO Box 8182

Elandsfontein, 1406

Johannesburg

South Africa

Tel: +27 11 820 7600Fax: +27 11 388 1136

E-mail: [email protected]

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

Date post:	03-Apr-2018
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03 Apron Feeder

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