Ronstan Orbit Series 55 Clockwise Ratchet Cheek Block

Item #


Product Description

Ronstan Orbit Series 55 Clockwise Ratchet Cheek Block


  • Automatic and Manual ratchet in one block

  • Up to 20:1 holding power

  • Easily fitted and securely retained Dyneema® Link head

  • Smooth easing of sheets

  • High performance cleating

    Sheave Ø - 2 5/32 in.

    Max. Rope Ø - 3/8 in.

    Max. Wire Ø - in.

    Pin Ø - in.

    Max. Working Load - 550 lb

    B. L. - 1540 lb

    Weight - 2.7 oz

    Product Information

    Automatic ratchet block

    Now you can enjoy the flexibility of setting up your ratchet blocks to suit yourself. Ronstan is the only company that offers a ratchet block with both auto and manual engagement modes*. In the auto mode of the ratchet mechanism engages when load is applied, but switches off when it's released. This lets the sheet run out smoothly and freely-great for rapid easing of the sheet and for gybing asymmetric spinnakers. In manual mode, the ratchet mechanism can be switched on or off as required. This is the preferred mainsheet set-up for may top sailors. Try the block in both modes and see which you prefer - you really can't go wrong.

  • Selected Series 55 models.

    Awesome ratchet block holding power

    Quite simply, Ronstan Ratchet Orbit Blocks™ have the highest holding power available. The sophisticated NC-machined sheave features Generation 2 of our patented sheave cross-hole geometry. Its holding power is up to 21:1, almost double that of our nearest competitor. The unique sheave design has 12 gripping faces which directly resist loaded line movement. Traditional designs have only 8 faces with an angled resistance to line movement. Our Generation 2 design has straight resistance faces which both distribute the load and minimize rope wear. These faces are offset from the radial line, to draw the rope down into the gripping area when under load.

    Simple and secure attachment

    The Dyneema® Link is easily fitted and is retained securely by a molded retainer clip. The flexible link can be left with one end attached to the block when fitting - no more lost shackle pins. The system is compatible with Dyneema®/Spectra® strops, webbing and caron connection points - much more so than steel loop tops or shackles. In auto mode, the sheet runs out smoothly and freely as soon as the ratchet mechanism disengages. In manual mode, the sheave cross-hole geometry eliminates the 'shuddering' run-out that you can expect from traditional v-groove ratchet blocks.


  • Dinghy mainsheet systems

  • Spinnaker sheets on dinghies

  • Control line applications on larger yachts


  • Sheave: Hard anodized Aluminum

  • Ball Bearings: High compression strength carbon black Acetal

  • Frame/Cheeks: Toughened, glass fiber reinforced Nylon

  • Rope Link: UV stabilized, multi-strand impregnated SK75 Dyneema®