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CMC Multi-Purpose Device

Version A

Version B

Version A Version B
Version A Version B

Overview


Version A
(#2767)

Front Rear Left Side
Front Rear Left Side
 
Front: Open for Rigging Rear: Open for Rigging Right Side
Front: Open for Rigging Rear: Open for Rigging Right Side

Technical Details

I acquired my 11 mm CMC Multi-Purpose Device (MPD) from Joseph Pilato in 2020.

This MPD is 143 mm. long, 193 mm. wide, 91 mm. high, and weighs 1194 g.

The MPD consists of a front plate with an attached parking brake mechanism, a swinging back plate, and several items between, including a pulley sheave, a moving brake, a fixed brake, and a secondary friction post.

The front plate is an irregular stamping made from 3.9 mm. aluminum alloy. The parking brake mechanism and its housing are attached to the outside of this plate with five round-head hex socket screws. Two of these also attach the secondary friction post to the inside of the plate, two attach a milled stainless steel fixed brake to the inside, and one attaches to the pulley axle. The first four are 1/4-20 UNC, the fifth is larger, probably 5/16-18 UNC. There is a sixth screw that attaches the housing from the inside; it is a countersunk hex-socket, probably 1/4-20 UNC. There is an arcuate slot that a "pin" on the moving brake rides in, as well as several 4.9 mm. holes that appear to be alignment holes for manufacturing. The top of the plate is bent inward with a 30° dog-leg. The top has a 22.8 mm. wide, 26 mm. high attachment eye, and the bottom has a 16.0 mm. diameter attachment hole, or "becket."

The rear plate is an irregular shape machined from aluminum alloy. The top of the plate is bent inward with a 30° dog-leg where there is a 22.8 mm. wide, 26 mm. high attachment eye that aligns with the eye on the front plate. The left side (viewed from the front) is bent forward to provide a rope guide. Most of the plate is 3.1 mm. thick, but the lower-right portion is thicker (6.1 mm.). a curves slot milled on the inside of the plate engages a tab on the fixed brake. The end of the slot limits how far the plate can turn when closing. A lip on the brake and one on the inside of the arc engage to help keep the rear plate from spreading open.

The pulley sheave is 15.4 mm. wide and 77 mm. in diameter. It has a 13.0 mm. wide, 10.9 mm. deep V-groove. The bearing is unidirectional and has some drag in the running direction (it will not spin freely).

The moving brake is a stainless steel casting attached to two 3.1 mm. thick steel arms and a third arm hidden inside the parking brake housing. The two visible arms straddle the pulley sheave and pivot on the pulley axle. The brake casting has a U-shaped rope groove. A machine screw holds the arms and casting together. This screw also serves as the "pin" that rides in the arcuate slot in the front plate. At one end of its travel the rope can run freely, but at the other the moving brake squeezes the rope against the inner side of the fixed brake.

The fixed brake is a milled stainless steel block secured to the front plate as described previously. It has a V-shaped notch that provides a 13 mm. diameter surface for the rope to bend over.

The secondary friction post is a stainless steel casting with a V-shaped notch on its upper surface.

The parking brake mechanism consists of a housing, a parking brake knob, a release handle, and some internal parts that are hidden from view. The housing is milled from aluminum alloy. It is bolted to the front plate as previously described. A raised rib on the outside limits the motion of the parking brake knob. This knob is milled from aluminum alloy. It is attached to the internal mechanism with a countersunk hex-socket screw, probably 1/4-20 UNC. In the unlocked position, it does nothing, but when turned to the locked position, an internal cam forces the moving brake to rotate about halfway toward the fixed brake. With the proper size and type rope, this holds the rope. The release handle is a milled aluminum handle attached to a steel rod with an allen screw. Pulling the resulting T-handle outward engages gear teeth on the handle and the hidden arm of the moving brake. Turning the handle with the teeth engaged relieves pressure on the parking brake cam, allowing the brake to be unlocked.

The front plate is printed with "CMC Rescue MPD™," "Pulley & Auxiliary, MBS 44 kN G," "Descent Control, MBS 23 kN L," "MEETS NFPA 1983 (06 ED)," the UL classified logo, "5F04," "Ø 11 mm," "Becket," and "29 kN." The parking brake housing is printed with a lock icon, a rigging illustration, "Always grip rope," a double-ended curved arrow around the parking brake knob, an unlocked lock icon, a book-with-an-"i" icon, and "Patented." The parking brake knob is printed with "Parking" and "Brake." The release handle is printed with a counter-clockwise curved arrow, " "Pull out & Turn to," "Release," and another counter-clockwise curved arrow. The inside of the front plate is milled with "11" and "MM." The rear plate is printed with "Manufactured by rock exotica," "usa," "11353M0076," a rigging illustration with the load labeled "kg," a smaller rigging illustration labeled "Extra Friction," and "Always grip Rope."

Comments

The MPD is intended for the technical rope rescue community, and so I will not give a full evaluation here. It is marketed as a pulley, a descent control device (not a descender), and a belay device (using the term in its rope rescue context, not in the normal climbing context).

The MPD is well made, but certainly too large and heavy to have any routine caving or climbing applications.

The internal gear mechanism appears susceptible to mud and dirt, and friends in the rescue community have told me that this is a problem.

The locking mechanism does not hold ropes that are smaller than the recommended size.


Version B
(#2767)

Front Rear Left Side
Front Rear Left Side
 
Front: Open for Rigging Rear: Open for Rigging Right Side
Front: Open for Rigging Rear: Open for Rigging Right Side

Technical Details

I acquired my 13 mm. CMC Multi-Purpose Device (MPD) from W. Fernandez in 2019.

This MPD is 145 mm. long, 192 mm. wide, 91 mm. high, and weighs 1172 g.

The MPD consists of a front plate with an attached parking brake mechanism, a swinging back plate, and several items between, including a pulley sheave, a moving brake, a fixed brake, and a secondary friction post.

The front plate is an irregular stamping made from 3.9 mm. aluminum alloy. The parking brake mechanism and its housing are attached to the outside of this plate with five round-head hex socket screws. Two of these also attach the secondary friction post to the inside of the plate, two attach the cast stainless steel fixed brake to the inside, and one attaches to the pulley axle. The first four are 1/4-20 UNC, the fifth is larger, probably 5/16-18 UNC. There is a sixth screw that attaches the housing from the inside; it is a countersunk hex-socket, probably 1/4-20 UNC. There is an arcuate slot that a "pin" on the moving brake rides in, as well as several 4.9 mm. holes that appear to be alignment holes for manufacturing. The top of the plate is bent inward with a 30° dog-leg. The top has a 22.8 mm. wide, 26 mm. high attachment eye, and the bottom has a 16.7 mm. diameter attachment hole, or "becket."

The rear plate is an irregular shape machined from aluminum alloy. The top of the plate is bent inward with a 30° dog-leg where there is a 22.8 mm. wide, 26 mm. high attachment eye that aligns with the eye on the front plate. The left side (viewed from the front) is bent forward to provide a rope guide. Most of the plate is 3.1 mm. thick, but the lower-right portion is thicker (6.1 mm.). a curves slot milled on the inside of the plate engages a tab on the fixed brake. The end of the slot limits how far the plate can turn when closing. A lip on the brake and one on the inside of the arc engage to help keep the rear plate from spreading open.

The pulley sheave is 15.5 mm. wide and 78 mm. in diameter. It has a 12.8 mm. wide, 10.6 mm. deep V-groove. The bearing is unidirectional and has some drag in the running direction (it will not spin freely).

The moving brake is a stainless steel casting attached to two 3.1 mm. thick steel arms and a third arm hidden inside the parking brake housing. The two visible arms straddle the pulley sheave and pivot on the pulley axle. The brake casting has a U-shaped rope groove. A machine screw holds the arms and casting together. This screw also serves as the "pin" that rides in the arcuate slot in the front plate. At one end of its travel the rope can run freely, but at the other the moving brake squeezes the rope against the inner side of the fixed brake.

The fixed brake is a stainless steel casting secured to the front plate as described previously. It has a V-shaped notch that provides a 13 mm. diameter surface for the rope to bend over.

The secondary friction post is a stainless steel casting with a V-shaped notch on its upper surface.

The parking brake mechanism consists of a housing, a parking brake knob, a release handle, and some internal parts that are hidden from view. The housing is milled from aluminum alloy. It is bolted to the front plate as previously described. A raised rib on the outside limits the motion of the parking brake knob. This knob is milled from aluminum alloy. It is attached to the internal mechanism with a countersunk hex-socket screw, probably 1/4-20 UNC. In the unlocked position, it does nothing, but when turned to the locked position, an internal cam forces the moving brake to rotate about halfway toward the fixed brake. With the proper size and type rope, this holds the rope. The release handle is a milled aluminum handle attached to a steel rod with an allen screw. Pulling the resulting T-handle outward engages gear teeth on the handle and the hidden arm of the moving brake. Turning the handle with the teeth engaged relieves pressure on the parking brake cam, allowing the brake to be unlocked.

The front plate is printed with the CMC Rescue logo, "MPD™, ’Pulley, MBS 44 kN "G,"’ ’Descent Control, MBS 23 kN "G,"’ ’Belay Device. "G" Ø13mm," "MEETS NFPA 1983," "(2012 ED)," the UL classified logo, "5F04," "Becket," and "33 kN." The parking brake housing is printed with a lock icon, a rigging illustration, "ALWAYS grip rope!," a double-ended curved arrow around the parking brake knob, an unlocked lock icon, a book-with-an-"i" icon, and "Pat. 7,658,264." The parking brake knob is printed with "Parking" and "Brake." The release handle is printed with a counter-clockwise curved arrow, " "Pull out & Turn to," "Release," and another counter-clockwise curved arrow. The inside of the front plate is milled with "13" and "MM" and is printed with a hand-holding-a-rope illustration and "ALWAYS Grip Rope!" The rear plate is printed with "Manufactured by rock exotica," "usa," "16314H0015," a downward-right-pointing arrow, "LOAD SIDE," a rigging illustration labeled "ALWAYS grip rope!," a smaller rigging illustration labeled "Extra Friction," and "Unlock Parking Brake To Load Rope." The fixed brake has a raised "2" cast into the outer side.

Comments

Most of the visible parts of the 13 mm. and 11 mm. MPDs appear to be identical, and the differences between my measurements of the two are within the limits of measurement error and typical manufacturing tolerance. The secondary friction post castings are different, but the differences are on the outer side and do not affect functionality. I do not know if there are internal differences, but I expect there are since I see no significant external differences.

The MPD is intended for the technical rope rescue community, and so I will not give a full evaluation here. It is marketed as a pulley, a descent control device (not a descender), and a belay device (using the term in its rope rescue context, not in the normal climbing context).

The MPD is well made, but certainly too large and heavy to have any routine caving or climbing applications.

The internal gear mechanism appears susceptible to mud and dirt, and friends in the rescue community have told me that this is a problem.

The locking mechanism does not hold ropes that are smaller than the recommended size.


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