Mechanical Advantage Systems: How Strong?

Roco’s Dennis O’Connell expands on the forces put on Mechanical Advantage systems.

In this and upcoming articles, we want to give you an idea of the actual forces that are put on M/A systems versus theoretical forces that you may read about. What’s the difference?

With theoretical, we’re referring to the amount of force that is “supposed” to be produced, while the actual is just that…the actual amount of force that is produced when the system is built and operated.”

For example, calculating the force if you built  a 3:1 mechanical advantage “on paper” (theoretically) versus physically building the system. With the actual system, you would have to consider the friction loss created by the system components, so the “actual M/A” may be 2.5:1 with the same 3:1 system.

Dillon 25,000 lbf dynamometer

We decided to do some informal testing out at the Roco Training Center with the assistance of some of our students. The systems were tested as they are generally used in the field. The numbers shown are an average of the tests we conducted. The average is from a random sample of 10 to 20 tests using the same equipment and set up. We used a Dillon 25,000 lbf dynamometer with an error factor of +/-20 lbf. Note: These test numbers are designed as a reference only and should not be used as exact force data.

Test #1: Straight-line Pull

Student Set-up: Students were asked to pull on the line in a horizontal plane and exhibit as much force as they could without tugging/jerking the line. They were then asked to maintain that tension and tug/jerk the line.

Equipment Set-up: 12-ft of 1⁄2” PMI rope tied with a Figure 8 knot and attached to the dynamometer by two 2-ft pieces of 1” basket-looped webbing and two auto-locking steel carabiners to a rigid anchor with another basket-looped webbing loop.

Students pull the line in a horizontal plane with as much force as possible without tugging/jerking the line. They were then asked to maintain that tension and tug/jerk the line.

What the Numbers Mean

First of all, they will serve as a baseline for future informal tests when comparing different types of M/A systems. We will evaluate the efficiency of the different systems as well as the possible forces that are put on the components of the system when using typical rescue haul teams.

Grasping at Ropes

One interesting fact that we can take away from these numbers is that even though the vast majority of the persons involved in the testing (random rescue students) weighed in excess of 160 lbs, they were only able to generate a maximum of 160 pounds of force on the 1⁄2-inch rope. This is largely due to the student’s ability to grasp and hold onto the 1⁄2” line before it pulled through their hands.

Similar tests using 9mm rope had an average force of 120 lbf for a single-person pull. There was only a slight difference of about 2 lbf between the 1⁄2-inch rope and the 9mm rope. We had anticipated a greater disparity as the rope diameter decreased and the ability to grasp the smaller line was lessened. However, we did observe that with the smaller diameter rope, haulers had a tendency to twist their hands making a 90-degree turn in the rope. This added additional friction making it possible to put more force on the line before it slipped.

Stay tuned as we continue this informal, real-world testing in future blog posts. It should be interesting to see how the forces translate from 1,2,3, and 4-person Haul Teams when using these various Mechanical Advantage systems.

Multiple Confined Space Entries

Physically inspecting and evaluating each particular scenario is the only way to ensure that OSHA compliance can be achieved with one Attendant when making simultaneous confined space entries.

QUESTION: What is required for making multiple confined space entries, and can an Attendant/Hole Watch monitor more than one entry at a time?

ANSWER: Good question! And, the answer is YES according to OSHA 1910.146. However, each space must be evaluated on its own merits with all regulations and requirements applying to each individual entry. Here we will provide some tips when considering one Attendant for multiple entries. This is also where preparing comprehensive rescue preplans becomes essential, and we’ll start there.

Suggestions for Writing Rescue Preplans

1.  One of the first things is to identify and categorize the space as “permit-required” or “non-permit required.” You’ll need to carefully consider the possible hazards based on the information gathered.

2.  Once you’ve identified the hazards, you’ll want to consider what actions might be taken to eliminate or control the hazard to allow for a safe entry. OSHA 1910.146 defines “acceptable entry conditions” as the conditions that must exist in a permit space to allow entry and to ensure that employees involved with a permit-required confined space entry can safely enter into and work within the space.

3.  Next, you would need to consider the type of work that is going to take place inside the space. A very important question to ask… could the work create its own hazard? (An example would include hot work being performed inside the space.) Then, what about rescue capabilities and requirements? Next, you’ll need to determine whether the entry should be considered “Rescue Available” or “Rescue Stand-by?”

Ratqa Rescue Team’s Commendable Rescue Effort

Since 1999, Roco has had the opportunity to train and equip rescue teams in Kuwait. The first team that we trained was the Kuwait National Petroleum Corporation (KNPC) Fire Officers that were assigned to three refineries located south of Kuwait City.  In 2001, Ratqa Contracting was tasked with providing a Technical Rescue Team at the same refineries and Roco provided the Technician Level training for this new team.

Roco provides Rescue Technician recertification training for
the Ratqa Rescue Team in Kuwait.

The Ratqa Rescue Team is comprised of contracted Filipino’s with the oversight of a Kuwaiti Rescue Officer. Management is committed to making sure the team receives Rescue Technician recertification every two years from Roco.

Two of our instructors from New Mexico, Tim Robson and Rich Pohl, have been the predominant instructors for this 19 member team over the years.  Both agree that this is one of the most competent and dedicated rescue teams they have ever taught.

On a recent recertification trip, Rich and Tim were made aware of an event by Lead Rescue Officer/Coordinator Mohammed Al-Raqum and Fire Officer Khalid Al-Habri. Both officers wanted to recognize the efforts of the team for an exemplary response to an unfortunate event. Both Rich and Tim thought this would be the perfect forum to recognize this excellent Rescue Team.

Lock-Out / Tag-Out: What Rescuers Need to Know

Dennis O'Connell, Director of Training/Chief Instructor

“The concept of LOTO is a great one and it works. As rescuers, we have to take the common industrial application and expand it to ensure that the rescue scene is safe and that we are controlling hazards at the point of contact with the victim or in a space where something has gone very wrong,” says Dennis O’Connell, Chief Instructor and Director of Training for Roco Rescue. 

Although commonly referred to as the “Lock-out/Tag-out” (LOTO) standard, the actual title of 1910.147 is “The Control of Hazardous Energy.” This title probably better describes it’s true purpose — and there’s no doubt that the understanding of this concept has saved many lives and prevented countless injuries.

The LOTO standard “covers the servicing and maintenance of machines and equipment in which the energizing or start-up of the machines or equipment, or release of stored energy, could harm employees.” It establishes OSHA’s minimum performance requirements for the control of such hazardous energy [Ref: 1910.147(a)(1)(i)].

March Pocket Guide Winners!

Roco will be giving away two Pocket Guides each month (one for industry, and one for municipal).

Brant G. from Thibodaux, Louisiana and Greg S. from Coldwater, Michigan were the lucky winners of Roco’s February Pocket Guide giveaway!

Roco will continue to give away two pocket guides each month. Stay tuned into our blog to see if you win! If you would like to purchase a  Roco Pocket guide visit our website or call 800.647.7626.

Rescue 1-Plus in North Vancouver

Rescue 1-Plus was held in North Vancouver, Canada, on March 19-23rd with Roco Chief Instructor Randy Engemoen.  This was a great group of rescue students, and you can see how well they did. Check out these action shots!