Thimbles

A thimble is a simple rigging element for fixing and holding steel wires and ropes. Thimbles are manufactured for wire ropes of various diameters.

Design

A thimble is a small-sized rigging part. It includes a special plate with a groove on the outside. The groove ensures long-term operation of flexible metal elements by eliminating abrasion.

Thimbles are used in construction for fixing various elements and in industry. They are manufactured for all rope diameters used in operational activities. The choice is based on the load and dimensions of the rope according to regulatory documents. GOST 2224 sets out tables and recommendations with parameters for verifying products.

According to the existing standards, the thimble diameter must exceed the rope diameter by at least 4 times.

Types of thimbles

Thimbles differ in characteristics, shape, and manufacturing method. By shape, thimbles are classified into the following types:

1. Round. A universal option used when rope loops are formed in a circular shape. Simplifies the loading and unloading process.
2. Guy (stay) thimbles. Used for reliable fastening or tensioning of all elements. The diameter of the product is lower than other variants, but the load capacity is up to 50% higher. In operation, the load on metal elements is minimized.
3. Marine (ship) thimbles. Used in shipbuilding for rigging. Produced by hot forging, which increases product strength. Products receive special marking depending on the type of rope they can be combined with. The designation also indicates the maximum lifting force in tonnes.
4. Wedge thimbles. A complex variant consisting of an insert, a housing, and pins. Used for fastening mechanical elements and lifting products, as they withstand high loads. Steel wire ropes are secured between the housing and the insert. Produced by casting and vary in performance characteristics depending on the metal. Thimbles made of material without pores or holes have increased strength. The presence of pores or structural holes reduces the load capacity and service life.
5. Closed thimbles. Made of metal alloys. Used for fastening synthetic ropes or natural ropes. Additionally equipped with side grooves and a closed housing, which prevents the rope from slipping during loading and unloading.

Operation

Thimbles for steel wire ropes are used in various fields, so several product variants are produced, differing in material. Thimbles may be used in the shipbuilding, construction, and automotive industries. The elements are used to secure steel wire ropes, synthetic and natural ropes.

Using the element extends the service life of ropes. Thimbles compliant with DIN 6899 protect the outer parts of the rope from defects, deformation, or abrasion. The use of thimbles in industry and operational activities is regulated by GOSTs.

Material and manufacturing method

Thimbles for ropes are manufactured by casting or hot forging from steel grades with a high carbon content. Reinforcements for operation at temperatures below −40 °C are produced from low-alloy steel grades. They are additionally coated with various metals for protection against oxidation. Zinc-plated thimbles are widely used in the automotive and shipbuilding industries.

How to choose?

To determine the suitable thimble, it is worth assessing the loads and ropes used. It is advisable to study GOST and regulatory documents. Take into account the operating conditions, environmental aggressiveness, and temperature to avoid damaging the product.