Direct Drive Crushing Sizers, specifically McLanahan Sizers, provide primary, secondary and tertiary reduction of friable, low silica materials such as coal, salt, gypsum, phosphate, limestone, bauxite, petroleum coke, lignite, trona, carbon anodes, oil sands, clay, shale and more.


Sizers have a direct drive arrangement and low-profile design that allows wheel mounting for a movable configuration. The preferred method of installation is to mount the unit on rails with a non-rigid connection between the feed and discharge chutes. Since the drives are attached to the mainframe of the sizer, the entire unit can be rolled out from the feed stream to facilitate maintenance.

Sizers are typically used in applications where the material being crushed has natural fracture plains and lends itself to compression crushing rather than attrition crushing or impact crushing. Coal, salt and phosphates are very common applications where Sizers are specified. They are also very well-suited to crushing applications where the product is found in high clay bands and requires liberation from the clay as well as size reduction.

Sizers are recommended for applications where a 4:1 ratio is required. However, due to the low profile and relatively small footprint, these Sizers are often nested to deliver multiple phases in a single flow.

How Sizers work

Sizers use an electric motor to drive the gear reducer, which is mounted directly to the roll shaft. The motor and reducer are protected via a fluid coupling fitted with a thermal element and underspeed sensors to eliminate the risk of shock loads or stall events transferring through to the drive components. The crushing rolls can be rotated either inward or outward at slow speed and high torque, which minimizes slippage and fines generation. Slow-speed Sizers are selected for the specific material and lump size to be crushed. Tooth profile selection allows the material to be grabbed and pulled into the crushing zone for maximum efficiency.

Sizers rotating inward utilize hydraulically adjustable roll shafts to ensure the product gaps between rolls are maintained. Outward rotating Sizers utilize adjustable crushing combs to account for wear and keep the crushing setting to specification. On each machine, crushing rolls are fitted with easily replaceable segments, which allows for much faster changeout and lower downtime. Intermeshing combs ensure removal of contaminants such as clays that can build up on other types of crushers.

McLanahan offers many different roll designs, tooth configurations and material selections that are engineered to maximize a sizer’s efficiency and wear life and to minimize the cost of ownership.

Why McLanahan Sizers

McLanahan is the world’s most experienced manufacturer of Double Roll Crushers and our Sizers operate around the globe. McLanahan Sizers are designed and manufactured to be more efficient and deliver a better total cost of ownership through the life of the equipment. McLanahan supports our Sizers for the life of the equipment and uses standard, readily available motors, gearboxes and couplings.

All segments and sizing combs in the Sizers are designed to be interchangeable throughout the machine. Unique to McLanahan Primary and Secondary Sizers is the hydraulic product size adjustment, which gives producers versatility if the product size requirements change.

Frequently Asked Questions About Sizers

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Sizer tooth wear can be checked by measuring tooth height from the base of the tooth and comparing this with the as supplied tooth height. A tooth profile template can also be used to compare a worn tooth profile with the original tooth profile. Hardface welding can be used to build up or maintain the tooth profile on some types of sizer teeth. Worn teeth will quickly reduce the throughput capacity of your sizer. Worn teeth will also suffer accelerated wear as the tooth height reduces, so it is important to monitor and maintain your sizer teeth.

The flow of feed material into a Sizer must be controlled to produce an even distribution along the full length of the rolls and to maintain an even feed split between the rolls. This ensures even wear of both rolls and even wear along the length of each roll and, in turn, maximizes the life of the consumable wear parts and the throughput capacity of the sizer.

The Sizer gear reducer shaft seals are typically grease-purged, double lip seals with a grease nipple and a grease vent. There is one input shaft seal and two output shaft seals, which should be greased once per week. Grease quantity should be sufficient to purge all used grease from the seal via the grease vent.

Sizer gear reducers are fitted with a sample valve on the oil drain port to allow regular samples to be taken for oil analysis. When changing gear reducer oil, the top inspection cover should be removed and the internals should be visually inspected for wear, damage or debris. The desiccant filter/breather should also be replaced when the oil is changed, or sooner if the desiccant beads indicate moisture saturation sooner (typically by turning red). Refill the gear reducer with the specified oil grade up to the fill level indicated on the sight glass. Note that the indicated oil level may increase or reduce when the drive is operating, but the oil fill level can only be checked with the drive stationary. Remember that the gearbox is at maximum life when the correct oil grade is used and cleanliness is maintained.

To replace worn Sizer segments, remove the threaded plug from the segment body and screw in the lifting eyebolt. Remove each of the segment hex-headed holding bolts. Lift the segment vertically using a chain block.

McLanahan Sizers deliver excellent control on product size and consistency.

Features & Benefits
  • Low roll speeds ensure minimum dust and fines generation
  • Direct mechanical drives
  • Compact design with right angle gear reducers and smaller footprint allow for installation in low-headroom areas
  • Product setting adjustability to make up for wear or change in product size requirements
  • Interchangeable segments and sizing combs throughout the machine
  • Rail-mounted to be rolled out from the feed stream to facilitate maintenance or tramp removal
  • A variety of roll designs and tooth configurations are available based on a customer’s application needs
  • Drive systems are available from globally recognized OEMs

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