Conveyor Safety Switches for Mining, Cement, and Bulk Material Processing FAQs

A:  The Ramsey Belt Misalignment Switch is used to monitor the position and tracking of conveyor belts. It is mounted on the conveyor structure and adjusted so the roller arm is the proper distance and angle from the outside edge of the belt. When a belt drifts out of alignment, it contacts the roller actuator arm which rotates the actuation shaft, causing the belt misalignment switch to send an alarm signal.

The actuation shaft has two cams inside the housing. Each cam actuates an independent SPDT micro-switch for alarm signals. The first micro-switch actuates with a 10° rotation of the actuation shaft for a warning alarm signal, allowing operators to address the situation before it becomes a problem. The second micro-switch actuates with a 20° rotation of the actuation shaft for a shutdown alarm signal in order to prevent or minimize equipment damage.

A:  The roller arm of the Ramsey Belt Misalignment Switch has internal stainless steel bearings. This allows the switch to be used on conveyors with belt speeds up to 1250 feet per minute with outstanding service life. With correct belt alignment there is no contact with the roller arm.

A:  A safety cable pull switch is used as an emergency shutdown device for conveyors or other equipment. Safety pull cables are attached to the actuating arm of the switch. When force is applied to the pull cable it rotates the actuating arm and actuating shaft. At a 20° rotation the switch enters a tripped and locked position. The actuating shaft has two cams inside the housing. Each cam simultaneously actuates an independent SPDT micro-switch for shutdown and alarm signals.

A:  Thermo Scientific Ramsey Safety Cable Pull Switches meet OSHA and MSHA requirements for safety shutdown devices. They are cCSAus approved for non-hazardous applications as well as CL II, Div 1 & 2, Group E, F & G applications.

A:  Standard safety cable pull switches include a manual reset lever. This lever keeps the switch locked in an alarm condition until it is manually reset by an operator.

A:  This tripper position switch is a heavy duty limit switch. It is often used to indicate the position of a tripper on a conveyor with multiple discharge points. However, it can be used anywhere you need an extremely heavy duty limit switch with physical activation.

The actuating arm of the tripper position switch uses a large acetal contact roller, 3 in diameter by 1.75 in wide. When the roller makes contact it rotates the actuation shaft which has two cams inside the housing. Each cam actuates an independent SPDT micro-switch for position or alarm signals.

The switch can be ordered with an option where one of the SPDT switches is actuated with clockwise rotation and the other SPDT switch is actuated with counter-clockwise rotation. This allows you to identify which direction the switch is activated from.

A:  The Thermo Scientific Ramsey Model SAS Snap Action Safety Pull Switch is a two-sided cable pull emergency stop switch. In addition it is designed to ensure that, should the cable become slack or is accidentally cut, the switch will activate so as to be repaired to normal functionality.

Pre-tensioned springs are installed at the extremity each side of the pull cord cable run. Cable tension is kept equal on both sides. In normal operation, should an emergency present itself, the cable is pulled in any direction and the pull cord switch’s arm rotates clockwise or counter-clockwise, thus activating the micro switches in order to alarm. If the cable breaks or becomes slack, the opposing pre-tensioned spring pulls the arm in that direction. The contact behavior for a cable that has broken is the same as pulling the cable. (See SAS Snap Action Safety Pull Switch Product Specification Sheet for additional details.)

A: Normally an operator needs to walk or drive alongside the conveyor looking for the tripped switch. An optional flag can help with visibility. Versions approved for Europe can have an optional addressable module.

For additional details about protection switches, please read the Ramsey Conveyor Protection Switches Product Specification Sheet.