Setting the Limits
The Spotline Practical uses a 4 pole rotary limit switch connected to the drive shaft with #35 chain. These hard limits need to be set each time the machine is installed and a new payload is attached. Let’s take a moment to familiarize ourselves with the rotary limit switch.
Inside the cover is a four layer CAM stack (think of it like a layer cake), each CAM layer corresponds to a physical limit circuit: FWD-ULT, FWD, REV, REV-ULT. The CAM stack rotates as the input shaft turns, activating the corresponding micro switch engaging the limit circuit. The CAM stack rotates CCW when the Spotline Practical is moving Forward.
There are 5 set screws on top of the limit stack used to adjust the position of each CAM. The center screw locks the CAMs in position while the four screws around the outside (noon, 3, 6 9) are used to adjust the CAMs. The limit switch will be damaged if the center locking screw is not loosened prior to adjusting the CAM positions. Also important, the locking screw must be tightened down after adjusting the limits or the limits will drift. With the basics of the rotary limit switch out of the way let’s take a look at how the limits are intended to operate.
The hard limits (set at the rotary limit switch) should be used as overtravel limits. During normal operation the limits should not be engaged - they are intended to stop motion if there is a failure or while manually jogging the machine. Take a look at the diagram below for a visual representation of where each limit is set based on total travel.
- 1.Using the onboard controls on the Spotline Practical, slowly move the payload to its highest safe position (Fwd) to ensure the cable feeds on the drum properly.
- 2.Pro Tip: leave a few inches of overhead in case the Ultimate FWD limit does not engage in the exact same place. Remember wire rope stretches over time, including the lifting cable’s core.
- 3.With the payload in its highest safe position, set the Ultimate FWD Limit by following the steps below.
- 4.Remove the cover of the rotary limit switch by removing two philips head screws and pulling off the cover.
- 1.On the limit switch, you will see a set screw with 4 smaller set screws positioned around the center set screw. The center set screw is the locking screw. Loosen (1 turn) the locking set screw with a flat-head screwdriver.
Caution: You MUST loosen your center set screw first. If you do not loosen the center set screw before adjusting the outside limit screws, you could damage your limit switch. The only way to fix this is by ordering a new limit switch.
- 1.The four smaller screws around the outside are used to adjust each of the individual limits’ CAMs. Each adjustment screw has a number and a color next to it, which corresponds to which layer (FWD ULT, FWD, REV, or REV ULT) it adjusts.
- 1.The rotary limit has 4 layers, each layer includes a CAM lever and a micro-switch to activate the individual limit.
- 2.Adjust the limit that you are setting by turning the corresponding set screw until the CAM strikes the switch.
- 1.Repeat steps 2.3-2.5 to set your other 3 limits. The steps below explain the location you should jog your machine to when setting each limit.
- 2.FWD ULT - Highest safe position.
- 3.FWD - Highest position that you would move the hoist to on a daily basis.
- 4.REV - Lowest position that you would move the hoist to on a daily basis.
- 5.REV ULT - Lowest safe position.
- 6.When you finish setting your limits, lock your center set screw to hold your newly adjusted limits. Then reattach the limit cover.
The Spotline Practical has a minimum load requirement of 5lbs. When the Spotline Practical is lifting less than 5lbs, the lifting line will have the tendency to become slack. To combat this problem, the Spotline Practical has a rod arm style limit switch wired into the ultimate limit circuit to detect when the lifting line has gone slack. The rod must be retained by the tension on the lifting cable, in order to move.
This feature prevents the lifting line from unspooling and getting caught inside the enclosure. When the slack line detection trips, you will usually need to add more weight to your lifting line. In some rare occasions, if the ultimate limit override was used to move through the slackline detection, the limit switch’s rod arm could slip in front of the lifting line and keep you in a constant ultimate limit state. To fix this problem, you will need to shut down the machine and manually reset the slackline limit. This can be done by breasting the lifting cable, so the rod arm is again behind the lifting cable.
The slackline limit switch comes to you factory calibrated to a minimum payload of 5lb and should not require adjustment. However, if the slackline limit switch is moved for any reason, then you can follow these steps to calibrate the switch. The resting position of the rod is locked by the screw on top of the pivoting head. When loosened, the rod’s resting position can be adjusted in 5° increments, so shift it 2 increments counter-clockwise or 10°, and then lock the adjustment screw. Without a load, the switch should push the lifting cable and trigger a slackline. Apply a 5lb load to the lifting line, and check that you can run the load up and down without triggering a slackline. If you find yourself needing help with adjusting the slackline switch, give us a call at 401-289-2942 x2, or drop us a line at [email protected].
Now that your machine is rigged and limits are set it’s a great time to test the motor and load brakes with the on-board test buttons. Combining the brake testing with limit setting during load in ensures it will happen on a regular basis.
Testing brakes can be hazardous without taking proper steps to ensure safety. The brake test functionality ensures that only one brake can be released at a time, so the load will not be released. However, if one brake fails it is possible for the load to fall. To reduce the likelihood of damage or injury we recommend lowering the load within 12” of the ground while testing the brakes.
- Before you conduct the test, check and see that nobody is working inside the machine or near test load.
- Jog the Spotline Practical so the payload (a 40lb sandbag would be a great choice) is 6-12 inches off the ground.
- On the Spotline Practical control panel, press the blue Enable button and the Motor button to release the motor brake. You should hear a click when the brake releases and engages.
- After testing the motor brake, test the load brake by pressing the blue Enable button and then the Load button. You should hear a click when the brake releases and engages.
- If during the Motor Brake test, the load falls to the ground, the load brake would need maintenance.
- If during the Load Brake test, the load falls to the ground, the motor brake would need maintenance. If you find that a brake needs maintenance, remove all scenery and do not operate the machine.
- Note: If you were to press the Enable, Motor, and Load button at the same time, the safety circuitry will not release both brakes at the same time.