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Cirrus 800 Power & Free System Information

Cirrus C-800 power & free conveyor system layout

 

 

 

 

 

 

 

Trailing or rear trolleys are positioned at the rear of a load bar and share the load with lead trolleys. The configuration of trailing trolleys allow accumulation to take place when subsequent lead trolleys come in contact with the tail on trailing trolleys.

 

Combination trolleys have leading and trailing trolley design characteristics built into a single trolley. These are used when small parts can be carried within an 8-inch horizontal plane without the need for a load bar.

 

P&F Stops

Stop mechanisms are placed throughout a system where loads are required to be stationary - such as in loading and unloading areas and segments of the conveyor where accumulation lines must be terminated. Most stops contain a pneumatic cylinder that controls the throw on a machined blade that serves two roles in stopping a load in transit. The blade provides a hard contact point for a leading trolley to stop against and the blade is shaped in manner that de-dogs (disengages) the pusher dog from the lead trolley as a result of the pusher dog's upward pivoting action.

 

Stop blade positions (extended or retracted) are monitored by sensors (proximity switches, reed switches or limit switches) to provide feedback to a central control system (typically a PLC). A solenoid valve mounted directly on the stop or remotely, controls the air supply to the stop cylinder.

 

P&F Switches

Track switches provide a means to divert loads from a main line to track spurs. Two types of switches are prevalent in systems.

 

Divert switches also known as unload switches are typically powered by a pneumatic cylinder that trigger a mechanical mechanism that directs a load off the main track onto a spur track.

 

Divert switch positions are monitored by sensors (proximity switches, reed switches or limit switches) to provide feedback to a central control system (typically a PLC). A solenoid valve mounted directly on the switch or remotely, controls the air supply to the switch cylinder.

 

Divert switches can be supplied for manual operation via pull cords.

 

Merge or load switches are triggered by an approaching lead trolley, not requiring any other means of power such as a pneumatic cylinder. Merge switches allow loads to divert from a spur back onto the main conveyor track.

 

Anti-Backups

Anti-backups are attached to the conveyor free rail, providing a secure means in which to prevent loads from rolling backwards. Constructed from a pivoting steel blade, anti-backups allow free trolleys to travel in a forward position only. Anti-backups are usually located at stop positions and along lengths of track that contain multiple carriers in accumulation.

 

P&F Sensor Actuators

Given the ability of stopping some loads while others remain in transit and the flexibility of switching loads to and from a multitude of tracks, power & free systems require logic controllers to facilitate orderly conduct of individual loads. This is accomplished through the help of sensors distributed throughout a typical system. In most cases sensors are triggered by mechanical devices that come in contact with various moving parts on the system including stop blades, switches and free trolleys.

 

Actuators that come in contact with free trolleys trigger limit switches or proximity switches to alert the presence or passing of a load at a specific location in the system. Momentary actuators also known as pork chops, signal the passing of a carrier. Maintained actuators or ski-bars, signal sustained contact with a carrier. Ski-bars are often used to indicate when the end of an accumulation zone is filled and when a carrier is occupying a stop.

 

 

 

System Specifications

 

Free Trolley Load Centres

Using a typical free trolley set (leading and trailing trolley) with load bar, the minimum load bar accumulation centres are approximately 15-inches. For very small loads a combination trolley without load bar can be used, offering accumulation centres of approximately 8-inches.

 

Pusher Dog Centres

Pusher dogs, consisting of a 4-wheeled chain link and cast dog, are installed in place of chain load bearings on any multiple of the minimum 8-1/8" centres.

 

Load Capacity

The maximum load that can be suspended from a 2-trolley load bar is 1,500 pounds. A single combination trolley can carry a maximum load of 750-pounds.

 

Chain Pull

Chain pull is the force required to overcome the rolling resistance of the conveyor chain. The chain pull on a given system is proportional to the individual load weights, load centres, quantity of elevation changes, quantity of horizontal curves and overall environment that the system operates in. An average system chain pull will typically range between 1.5% and 5% of the sum of the moving load. Maximum chain pull for a single caterpillar drive is 750-pounds.

Contact Cirrus for chain pull calculations that relate to your system.

 

Typical System Components

 

Power Rail Components

See our Series 800 Conveyor System page for details on the power components of Cirrus 800 Power & Free.

 

Pusher Dogs

Pusher dogs provide the connection between the powered chain and the free rolling trolley / load bar assembly that carries product loads. Pusher dogs, consist of a 4-wheeled chain link and cast pivoting dog installed in place of chain load bearings on any multiple of 8-1/8" centres. The claw dog is attached to the 4-wheel trolley body with a clevis pin to allow for dog replacement without having to break the conveyor chain.

 

P&F Track

Straight track is comprised of roll formed 5/32" wall enclosed track positioned over a pair of 3-inch channel tracks, all tied together with flame cut track yokes.

 

The overall track dimension, measured from the top of the track yoke to the bottom of the 3-inch channels is 11-inches. The overall width including track yoke measures 9 1/16" inches. Track is finish painted medium blue and is available in 10 and 20-foot lengths. Stainless steel track is also available, providing long life in challenging environments such as parts washers.

 

Each system will contain at least one chain installation gate which may also serve as an inspection port for the power chain. This straight section of track is hinged on one side, allowing access to the chain. There is also an inspection gate that hinges on the top to provide access to the chain. The overall length of an inspection section is 27-inches.

 

Each system will also contain at least one free trolley installation gate. This gate allows open access to the 3-inch channel track where free trolleys can be installed or removed from the system.

 

Oven expansion joints are required in long straight runs of track to compensate for thermal expansion in ovens.

 

P&F Horizontal Track Curves

Horizontal curves are formed from straight enclosed track sections and roll formed 3-inch channel tracks, all tied together with flame cut track yokes. Common radii available include 24, 36 and and 48-inch centreline radius. The most common are 24-inch centreline radius. Curves are typically shipped in segments of 30-degree, 45, 60, 90 and 180-degrees.

 

P&F Vertical Track Curves

Vertical track curves are formed from straight enclosed track sections and roll formed 3-inch channel tracks, all tied together with flame cut track yokes. In order to complete a change in elevation, two types of vertical curves are required. A lower vertical curve leads the chain from level to an incline and a top vertical curve takes the chain from an incline back to a horizontal position. Straight track situated between the vertical curves can be added to increase the overall incline or decline of the elevation change.

 

Track elevation changes use tight bite track to ensure that loads can never disengage from the claw dogs. Standard straight track has a drop of 6-inches (measured from the bottom of the power track to the bottom of the free track). Tight bite track arranges the power track and free tracks closer together (5-1/2" on declines, 5-1/8" on inclines) which results in no available space for the claw dog to pivot clear of the leading trolley. Transition sections of track are used leading into and exiting elevation changes to match the tight bite track drop dimension.

 

Two radii of vertical curves are available - 36-inch chain centreline radius and 48-inch chain radius. The most common are 36-inch centreline radius. Curves are typically shipped in segments of 30-degree, and 45-degrees.

 

P&F Accumulating Trolleys

Free trolleys, usually in combination with a load bar, carry product loads. Trolleys are manufactured from steel castings that come with axles, four load bearings and two guide rollers.

 

Lead trolleys are positioned at the front of a load bar in the direction of travel. Pusher dogs, mounted on the conveyor chain, engage on the lead trolleys to propel loads throughout the system. The method in which the pusher dog engage lead trolleys also ensures that loads remained captured when transitioning track declines through changes of elevation.