Apron Feeders

Design and Features

The Concept
An Apron Feeder consists of the following parts:
• A series of overlapping Heavy Duty Pans (or Flights) that carry the material. 
• The pans are connected on each side to Roller Chains and Traveling Wheels. 
• The roller chains are propelled by a Drive Pulley and Shaft and Chain Sprockets
• The drive shaft and sprockets are rotated by a Drive Mechanism. 
• A Tail Shaft and chain sprockets and a Screw or Hydraulic Tensioning Mechanism
• A High Pressure Lubrication System
• All these parts are mounted to a robust Steel Main frame.
• Auxiliary equipment may include a feed chute, a discharge chute and a clean up or Dribble Conveyor underneath.

FLSmidth AFD series Apron Feeders use sealed-for-life- maintenance free tractor components and are available from 900 mm to 4000 mm widths and capacities in excess of 12,000 tons per hour

The Pans
The Carrying Pans are typically constructed of welded steel plates or Cast Manganese.  Their design and manufacture is critical since they are subject to high impact and severe wear that can result in cracking, premature wear and early replacement.

Flow Control
An Apron Feeder can regulate the flow of material based on volume. The pan speed and the gate cut off height can be regulated to provide an even volumetric feed down stream. 

Pin gates, also called Spile Bars, or Needle Gates can block off the in feed for maintenance.


Drive Systems

Drive Types
Several types of drive systems are available depending on the application, preference and cost.

All include an electric motor, a reduction mechanism and often a speed adjusting device.

Hydraulic Drives
Hagglunds provides a Low Speed High Torque hydraulic drive that is very common for apron feeder applications.  Their robust design, variable speed and ability to provide full starting torque for an unlimited time provide advantages in this high-load application.  Above all, Hägglunds drives have a unique capacity to handle the starts, stops and heavy shockloads common to feeder operation.

An alternate type of hydraulic drive is based on a conventional electric motor and gear reducer.  A separate hydraulic motor (driven by the reducer) is required to control the speed.

Variable Frequency Drive VFD
Because of advances in technology and cost competitiveness, Variable Frequency Drives are growing in popularity. The parts include an electric motor, a planetary reducer and the VFD. Speed adjustment is all electronic.

FLS is a leader in this technology and has installed some of the largest highest tonnage feeders in the world with VFDs.


Experience and Photos

Copper Mine Peru	Gold Mine Australia	Cement Plant USA