Triple Blocks – Details

Another post on pulleys?

When I first started lifting logs, I used a chain hoist, some antique #8 pulleys, and some homemade pulleys when I couldn’t find any more antique pulleys.

Pulleys that are rated for more than 3,000 pounds are surprisingly hard to find, and the ones you do find can cost over $400 per block. Pulleys are rare because everyone hires a crane or uses a telehandler to lift heavy stuff anymore. If you are having trouble finding a telehandler due to the recent construction boom, you may want to consider using block and tackle. A set of block and tackle consists of two pulleys working together. You need at least two sets – one on each end – to lift a log. Four sets means you don’t have to move the pulleys every time you lift.

Pulleys are also great for moving things horizontally – pulling logs out of the bog instead of getting stuck back there with your tractor. Or lifting 500 lb window frames up to the second floor to install them. The uses are many.

A guy I met on facebook is wanting to build a cabin up in Tennessee and asked me to build him two sets. I went and looked at my original post, and I left out a lot of details. This post should remedy that issue.

Parts

For each set of blocks, you’ll need 6 single pulleys and 4 bolts – details below.

  • 6 @ Harbor Freight 4 inch / 1 1/2 ton blocks – inventory number: 63693
  • 2 @ 7/16″ x 5″ grade 5 or better cap bolts
  • 2 @ 7/16″ lock washers
  • 2 @ 7/16″ nuts
  • 2 @ 1/2″ x 5″ grade 5 or better cap bolts
  • 2 @ 1/2″ lock washers
  • 2 @ 1/2″ nuts

Assembly

Parts – see photo:

Parts diagram. Not completely shown: 7/16″ & 1/2″ bolts.
Starting the assembly.
  1. Disassemble all the pulleys with wrenches or sockets. Save all the parts. You will be building two types of pulleys – a regular pulley, and one with a becket. The becket is where you tie the end of the rope. Each set of pulleys contains one of each type, and the one with the becket is the top pulley.
  2. Begin assembling a triple block:
    1. Place a 7/16″ washer (9) on the 7/16″ bolt. Do the same (8) for the 1/2″ bolt. Push the 7/16″ bolt through the center hole of one of the black plates, and the 1/2″ bolt through the bigger top hole of the same plate (3).
    2. Place a pulley spacer (4) over the 7/16″ bolt, and a sleeve spacer (5) over the 1/2″ bolt. Also place a hook (6) over the sleeve spacer.
    3. Place a pulley (7) over the 7/16″ bolt on top of the pulley spacer.
    4. Place another pulley spacer (4) on top of the pulley.
    5. Put another black plate on top of this sandwich.
    6. Repeat steps 2 – 5 until the last plate is in place. Also don’t place a hook in the middle area. There should be a spacer on both sides of each pulley.
    7. Place two more washers – one on each bolt, then add lock washers and nuts. Tighten until snug.
  3. For a block with a becket (an attachment point for the rope), place an extra plate after step 2.4 (next to the center pulley) and another plate after the second middle plate. These plates should point the opposite direction of the other 4 plates. Also use one of the original bolts (1) and a washer (8) and nut (10) from the package. See photo.
Pulley with becket on right. The other pulley is similar except it doesn’t have a becket.

Reeving the blocks (threading the rope)

There are a lot of instructional videos on this topic – here is one that seems clear.

Or if you like diagrams, use this one:

Use and care suggestions

Hang the pulley with becket on a tall pole. I find the 6,000 lb lifting straps sold at Harbor Freight handy. Use a slip knot in the strap so it will cinch up tight to the lifting pole. However high you hang the pulley, figure you can lift a log to that height minus 4-6 feet. So if your pulley is 20 feet from the ground, you should be able to lift up to a height of 14′-16′.

Hang snatch block (a single pulley) at the bottom of the pole to redirect the rope from vertical to a horizontal point. This will make it possible to just tie the rope to your car and drive away, causing the log to lift. Here’s a handy video on how this works.

Use 5/8″ triple ply poly rope (“Boat dock rope”). It’s easy to splice. My heaviest log weighed around 6,000 lbs. The pulleys lifted it no problem.

Check the nuts and bolts on the pulleys at least daily to ensure they are snug before lifting. Dropping a 3-ton log from 16 feet in the air is really scary. Keeping them out of the rain is a good idea, but not absolutely necessary unless you plan on leaving them for the winter – don’t do that – take care of them.

I have another post on using knots. It contains information on how to splice triple ply rope so it can be threaded back through a pulley.

Now go lift some logs!

2 thoughts on “Triple Blocks – Details

  1. Been reading your blog since I found it , not long after you started . Am impressed with your creativity and work ethic . Just made my own block and tackle set using your design . A small modification I added was to use the original third sleeve spacer to cover the threads of the becket bolt and make a new one from 1/2 EMT (electrical conduit ) 1 1/4 long to fill the space between the plates at the top of the pully assembly . This allowed me to tighten the 1/2″ x 5″ bolt without putting lateral pressure on the center plates .I doubt this is necessary , but I thunk of it, so I done it . I need to pull several trees out of a pond ( felled by consarned beavers ) and I reckon this gear will do it . I look forward to following your progress . Jake

    Liked by 1 person

    1. that’s awesome. I like improvements. I always felt like the threads on the becket bolt would eventually wear through the rope, so this is a great idea.

      Like

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