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Block Stop
Promalp Traxion
Friendship-2
Friendship-2.1
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| Block Stop | Promalp Traxion |
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| Friendship-2 (Дружба-2) |
Friendship-2.1 Guru (Дружба-2.1) |
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Block Stop|
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| Front View | Rear View | Side View |
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| Front View: Open for Rigging | Rear View: Open for Rigging |
I acquired my Krok Block Stop from Gear4Rocks in 2012. Immediately thereafter, I received a second one when Alex Dniprovsky sent me a box of donations originating from Alex Kostromitinov, the CEO of Krok. Gear4Rocks is the same company as Krok, the only difference is that the Krok trademark sells gear only inside the Ukraine, and the Gear4Rocks trademark was created to spread Ukrainian gear around the world.
My Krok Block Stop is 60 mm. long, 176 mm. wide, 42 mm. high, and weighs 444 g.
The Block Stop consists of a sheave on a pivoting arm between two side plates. The sheave is turned aluminum alloy, 49.2 mm. in diameter and 16.2 mm. thick. It has a 12.7 mm. wide, 67 mm. deep U-shape rope groove turned in the edge. A central hole allows it to rotate directly on a 9 mm. shaft (there is no separate bearing). The shaft is 25.1 mm. long, with the outer 3.3 mm. turned down to 6 mm. for riveting to the arm plates, leaving 18.5 mm. between the plates. The arm has two side plates made from plated steel. Each arm plate is 120 mm. long, 28 mm. wide, and 3 mm. thick, is wounded at the sheave end, and angled at the other. There are three pins riveted in place at the end opposite the sheave. Two are 8 mm. diameter cylinders, the third has a shallow 13 mm. wide, 1.0 mm deep U-shaped groove. The arm rotates on an 8 mm. pin set 51 mm. from the sheave axle. Two flat washers keep the arm centered between the side plates. The side plates are also made from 3 mm. plated steel. They are 154 mm long, 30 mm. wide, and have a 40° bend at the arm axle, 118 mm. from the top. One side plate pivots on the arm axle. The tops of the plates are dog leg bent inward until they touch, and a 13.6 mm. attachment hole is punched through each plate. A 42 mm. long, 10 mm. diameter pin is attached to the other end of one side plate with an 8 mm. jam nut and a washer. The pin has a turned groove, and a hook in the other side plate engages this groove. A set of 5.9 mm. hole passes through the side plates and arm plates 15 mm. above the arm axle. A pin (not supplied) placed through the four aligned holes would disable rotation of the arm and pivoting side plate.
There are no markings on this device.
The Block Stop is a capture pulley that does not require an aggressive cam; instead, the rope is squeezed between the turned arm pin and the lower side plate pin. This arrangement is not as secure as a toothed cam, but it is also less likely to cause rope damage when overloaded. The rope can slip under load (according to Krok, at 900 kg). This can be a safety feature or it can be a hazard, depending on the application. The Block Stop is rated for 3000 kg.
The sheave does not have a roller bearing, so it has great friction and is more susceptible to wear.
The Block Stop was discontinued in late 2012.
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Warning: The rope can slip under load. This can be a safety feature or it can be a hazard, depending on the application. |
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| Front View | Rear View | Side View |
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| Front View: Open for Rigging | Rear View: Open for Rigging |
I acquired my Krok Promalp Traxion from Gear4Rocks in 2012.
My Krok Promalp Traxion is 56 mm. long, 124 mm. wide, 29 mm. high, and weighs 280 g.
The Promalp Traxion is a conventional hauling pulley with two side plates, a steel sheave, and a spring-loaded cam. The side plates are made from 3.9 mm. thick aluminum alloy. Each plate has an upper corner bent inward and a 14.1 mm. attachment hole is punched at this location. Five 9.7 mm. lightening holes are spaced around the sheave axle. One plate pivots on the sheave axle. This plate has a cutout on the right side to allow access to the cam.
The sheave is a 42 mm. diameter, 14.2 mm. thick steel turning with a 10.5 mm. wide, 2.7 mm deep U-shaped groove turned on the circumference. The sheave is equipped with a ball bearing.
The cam is a painted steel casting with conical teeth arranged in a (3.2)(2.2.H)^3(2.2.3.2) pattern (where "H" represents a subtriangular mud hole). The cam is mounted on a pin riveted to the fixed side plate, A spring on this pin acts to close the cam. A second pin supports the other end of the spring. The cam has a spring-loaded plunger that can be used to hold the cam open, allowing one to use the Promalp Traxion as a standard pulley.
The front plate is stamped with the Krok logo and a book-with-an-"i" icon. The rear is stamped with the month and year of manufacture, "04 11."
When I received my Promalp Traxion, the cam plunger was very difficult to operate; however, once I got it working, it actuated easily. The problem was that the paint had glued the pin in position, and I simply had to break it loose. Unfortunately, if I let the Promalp Traxion sit unused, the paint seems to set up again.
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| Front | Rear | Top |
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| Front: Armed | Rear: Armed |
I acquired my Friendship-2 from Krok in 2021.
My Friendship-2 is 113 mm. long, 128 mm. wide, 48 mm. high, and weighs 492 g.
The Friendship-2 is a double hauling pulley with two shells bolted together, two aluminum sheaves, two spring-loaded cams, and an arming lever that acts on a shock cord loop connected to the cams.
The shell plates are made from 1.9 mm. thick steel sheet metal cut, bent to shape, and painted. Each plate has rope channel on the bottom side and a cam channel on top. A 14.8 mm. hole above the sheaves provides an attachment point for the anchor.
The cams are cast from steel and painted. Each cam’s radius increases from 37 to 58 mm. over an angle of 42°, giving a 31° cam angle. The tooth pattern is (3.2.2)(1H1.2)^3(2.3.2) where "H" represents a subtriangular mud hole.
The cams are connected by a loop of 2 mm. shock cord. The cord passes inside two guide bollards and over the activation lever mounted on top of the shells. The lever has a notch near its pivot that can capture and tension the shock cord when the lever is activated.
The aluminum alloy sheaves are 52 mm. diameter on the outside, 40 mm. on the inside, and 15.7 mm. thick. A 12 mm. wide U-shaped groove turned on the circumference reduces the central diameter to 27.2 mm. Each sheave is equipped with a ball bearing.
The front rope channel is printed with "MBS 15 kN," a hollow up-pointing arrow, "WLL 4 kN," ’"Дружба-2",’the Krok logo, "1809.1115," and a book-with-an-"i" icon. One ball bearing is marked "608Z" and the other "МП" and"80018," but since only one side of each bearing is visible, they may converse markings on the other side.
The Friendship-2 is designed for tensioning double-rope horizontal lines with diameters from 8 to 12 mm. The shock-cord and lever mechanism allows one to easily release tension by arming the cord, pulling the ropes slightly into the device, and then letting the ropes out. This is a clever idea, but it only works if the shock cord provides enough tension to lift the cams. When my Friendship-2 arrived, the cords had relaxed enough that they did not provide enough tension to hold the cams away from the rope. This video shows how well it works once you get everything adjusted properly:
Of course, the Friendship-2 can also be used as a normal hauling pulley.
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| Front | Rear | Top |
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| Front: Open for Rigging | Rear: Open for Rigging | Bottom |
I acquired my Friendship-2.1 Guru from Krok in 2021.
My Friendship-2.1 is 86 mm. long, 138 mm. wide, 53 mm. high, and weighs 550 g.
The Friendship-2.1 is a double hauling pulley with two shells bolted together, two aluminum sheaves, and two spring-loaded cams with cam-mounted safeties.
The shell plates are made from 1.9 mm. thick steel sheet metal cut, bent to shape, and painted. Each plate has rope channel on the bottom side and a cam channel on top. Two 14.6 mm. holes above and beside the sheaves provides an attachment point for the anchor.
The cams are cast from steel and painted. Each cam’s radius increases from 37 to 58 mm. over an angle of 42°, giving a 31° cam angle. The tooth pattern is (3.2.2)(1H1.2)^3(2.3.2) where "H" represents a subtriangular mud hole.
The aluminum alloy sheaves are 52 mm. diameter on the outside, 40 mm. on the inside, and 15.7 mm. thick. A 12 mm. wide U-shaped groove turned on the circumference reduces the central diameter to 27.2 mm. Each sheave is equipped with a ball bearing.
The front rope channel is printed with "WLL 4kN," with "Мах. 300 кг" inside, "MBS 140kN," ’"Дружба-2.1",’the Krok logo, "1901.0512," and a book-with-an-"i" icon. The other rope channel is printed with "GURU." Each ball bearing is marked "CRAFT" and "608Z."
The Friendship-2 is also designed for tensioning double-rope horizontal lines with diameters from 8 to 12 mm. It uses traditional cam safeties instead of the clever, but sensitive shock cord arrangement that the Friendship-2 uses.
[ Top | Block Stop | Promalp Traxion | Friendship-2 | Friendship-2.1 ]
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