Continue with onX Maps
Sign in with Facebook
6mm micro pulley
|
At only 17 grams with a 2 kN WLL the DMM Helix Polo micro pulley is something I would like to have for a 7:1 double mariner haul kit but they appear to be vaporware. Is there anything similar on the market? |
|
I use the Ronstan orbit on my rescue hauler, weighs 9g, MWL 250kg BL 550 kg and better bearings. |
Jim Titt wrote: I bought one. How do you attach yours? It comes with 1.7mm spectra-core lashing line but it also says up to 4mm will fit. Could a single 4mm loop be used as both lashing and Prusik? |
|
I've the supplied Dyneema on one and some 4mm polyester high-strength cord on the other because I needed a larger loop/becket as I'm using three together. |
|
Pass the cord through the pulley and tie a sliding grapevine bend, a double fishermen’s that captures both sides of the loop. |
|
I knew it would be small but in hand the Ronstan Orbit Series 20 pulley is tiny! Can it really handle a working load of 2 kN while keeping an efficiency advantage over a carabiner or ring? |
|
Clever guys at Ronstan, probably the world leaders in stuff for small boats. Rather than using a standard ball bearing or a bronze bush there's a double row acetal ball bearing and when the load gets high there's an acetal bush running on the stainless centre pin. Exactly when the bush takes over I don't know, whichever it's going to be far better than over a biner. I could measure it if I can summon up the energy to bring some heavy weights in the workshop! |
|
I lifted a 88kg weight, block at the top and pulling downwards so 1:1. 4mm cord. Load pulling (it's really a force but that's confusing). Efficiency corrected for the weight of the load cell in % Ronstan 98kg 85% 12mm karabiner (new) 120kg 61% Petzl block 96kg 86% Edelrid block 100kg 83% Roll'nLock 98kg 85% The Roll'nLock was a problem, the cord preferred to move to the side and gave erratic readings as well as one time chopping the cord. |
|
I am grateful. Thank you! Is this a good cord for these blocks? https://www.fisheriessupply.com/fse-robline-dinghy-control/dc-4y |
|
Better than I'm using! |
|
Recently was going to place an order with them and got a shipping charge for $125 for $50 of line, free shipping over $99 though. That is some nice cord, knots easily. |
|
Thanks Brocky, I got the idea from one of your posts. I ordered from westcoastsailing.net (corrected) as they had other lines by the foot I wanted. I also ordered an Orbit Series 30 block so I can rig the systems shown below, in addition to the 3:1, 5:1, and 7:1 shown in Eight Simple Systems using a single cord block that I had originally planned.   |
|
The Orbit 20 block lashed with four feet of 4mm Marlow Excel Racing GP78 for use as a Prusik, with a blended Technora sheath for heat resistance. 22 grams. Coils to the size of my thumb.  |
Webfoot wrote: Is this the same one? https://www.amazon.com/Ronstan-Ball-Bearing-Orbit-Block/dp/B0063K6PFA |
|
Yes. |
 |
|
A "little less"? |
