Maintenance & Warnings


Before leaving our manufacturing facilities all parts that require grease are lubricated with multipurpose, polyurea petroleum based grease of medium consistency. This does not relieve the end user of their responsibility of periodic lubrication. The following is a general lubrication schedule. The frequency of inspection and lubrication should be based on the frequency of use, harshness of environment, climatic conditions, and the user’s own maintenance and lubrication schedules.  


Bronze Bushings:  

(Non self-lubricating type) every 8 hours of normal continuous operation, twice a month for normal intermittent use, or monthly if seldom used.  

(Self-lubricating type) this type of bushing should never be greased. A light oil reservoir system is recommended under severe conditions.  

  • Roller/Ball Bearings - Every 24 hours of normal continuous operation, twice a month for normal intermittent use, or monthly if seldom used. 
  • Tapered Roller Bearings - Every 40-48 hours of normal continuous operation, or once a month for intermittent use. 

Thrust Bearings and Thrust Washer Lubrication:  

  • Thrust Bearings - Twice a month for frequent normal swiveling or every 3 weeks for intermittent normal swiveling and/or straight static loading. 
  • Bronze/Brass Thrust Washers - Once a day for frequent normal swiveling or every 3 weeks for intermittently normal swiveling and/or straight loading. 

STORAGE CONDITIONS: If parts have been stored outside without adequate cover, bearings (particularly Roller, Ball, or Tapered Bearings) should be checked monthly and lubricated to reduce the risk of corrosion between matching metal parts. Before initial startup of stored equipment, it is highly recommended that parts be cleaned and lubricated prior to use, regardless of the last scheduled lubrication period.  

WORKING LOAD LIMITS: All ratings shown in Skookum literature are based upon the item being new or in “as new” condition. Catalog ratings are considered to be the greatest load that should be applied to the item. Therefore, abnormal loading must be taken into consideration when selecting the item for use in any system. Continuous rapid shock, or surge loading, i.e. high cycle loading will rapidly reduce the Working Load and the life of the product. These conditions require more frequent inspection and testing, including additional N.D.E. (Non-destructive testing/examination). Catalog ratings are based upon typical environmental conditions. Consideration must be given to item selection when unusual conditions are to be encountered. All ratings are in U.S. short tons of 2,000 lb per Ton. The products shown are to be used in a tension or straight pull manner. Caution must be used to prevent the product from being subjected to side loading conditions that would cause additional and/or unintended loading. All hook latches are intended to retain loose slings or devices under slack conditions. They are not intended to be antifouling devices. Caution should be to prevent the latch from supporting any part of the load. Periodic inspection of latches must be made to insure a proper operating condition. Grinding, welding, and/or weld repair of any of our products without written consent by our company voids all warranty, whether written or expressed. It is recommended that you contact our engineering department for consultation before attempting any type of repair by welding or grinding. Line sizes expressed in our catalog refer to regular 6 x 19 construction wire rope, not swaged rope.  

INSPECTION AND WEAR: Wear, misuse, overloading, deformation, intentional alteration, and other usage factors may necessitate a reduction in the product’s working load rating, or a reduction in its design factor rating. It is recommended that all products be inspected on a regular basis to determine their serviceability. It is necessary to clean and inspect all items on a regular basis and keep accurate records of the inspection. The minimum industry standard is daily visual inspection and a monthly written and recorded inspection. Things to look for and inspections to perform include (but are not limited to) the following:  

  • Marks, nicks, gouges, scuffing, and cracks. 
  • Wear, especially excessive wear at load bearing points and threaded parts. 
  • Twists or bends in forged shackles and hooks. 
  • Unauthorized grinding, welding, cutting, or high heating conditions 
  • Opening or stretching of hooks, shackles and links 
  • Loose or worn retaining latches on hooks 
  • Loose nuts, pins, or missing cotter/clip pins 
  • Mushroomed contact points on shackles, hooks, and striking faces on hammers and splitting devices. 
  • N.D.E. Inspection as warranted (non-destructive testing examination such as Magnetic Particle, Die Penetrant, Ultrasonic, and/or X-Ray) 

Any item showing evidence of, or failing any of the above inspections should be immediately removed from service. Items may be returned to Skookum (freight prepaid) for professional inspection for a minimum charge. If the item cannot be reworked or repaired, or is in an unsafe condition, we will notify the customer immediately and make arrangements for the disposal of the item.  


Knowing the correct terminology of the load ratings helps in specifying the correct item for your application. The following load definitions are the ones most commonly used in our industry: Working Load or Working Load Limit The maximum recommended load that should be applied on the item. The terms Working Load (WL) and Working Load Limit (WLL) refer to straight in-line pull with respect to the centerline of the item unless otherwise noted.  

PROOF LOAD The average load to which an item may be subjected to before visual or permanent deformation occurs. It also refers to a testing procedure where a load is applied in the performance of a proof test.  

ULTIMATE LOAD The weighted average load at which the item being tested fails or will no longer supports the load.  

SHOCK LOAD Is a resulting load caused by the rapid change of movement such as impacting or jerking of a static load. A shock load is typically significantly greater than the static load. In some cases it will double the static load instantaneously and should be avoided as both a potential hazard to equipment operators and to the equipment itself.  

DESIGN FACTOR: This is an Industry term denoting theoretical reserve capability. This is usually expressed as a ratio such as 4 to 1 or 5 to 1 (4:1 or 5:1). It is normally determined by dividing the rated ultimate strength by the stated working load limit (WLL). It may also be based as a weighted average (as per the ultimate load definition above), or as a minimum factor. In which case the ultimate tested load meets or exceeds the stated design factor. Terms to be avoided or not to be used at all: Safe Working Load or Resultant Safe Working Load are not accepted terminology and do not denote specific product capabilities. Working Load or Working Load Limit are the proper descriptors. Safety Factor is not an accepted terminology. Design Factor is the proper descriptor.  

IMPORTANT NOTE REGARDING FORESTRY PRODUCT RATINGS: Skookum Forest products are designed to be used with and tested with Wire Rope conforming to the following description:  

  • New 6 x 19 or 6 x 37 Class, EIP, IWRC, Right Regular Lay Wire Rope made to US specifications. 
  • Used for Logging / Skidding or Pulling Applications 


This guide covers the application and maintenance for the Skookum, B.C.M., RopeMaster, and Ulven Brand Shackles and Rigging. It also includes the Skookum and Ulven Brand Blocks and Rigging products.  

SKOOKUM SHACKLES: Skookum Shackles are Forged Alloy Steel, and meet or exceed the criteria of ASME B30.26, Chapter 26-1, and/or the Federal Specification RR-C-271.  

DESIGN FACTOR: The Design Factor on standard catalog Skookum Shackles are based on a minimum of 5 to 1 (5:1). The Design Factor (ultimate capacity) is arrived at under ideal and controlled conditions and should never be used as a basis for reverse design engineering.  

WORKING LOAD (RATED LOAD): The working load or rated load is the maximum load that should be exerted on the item.  

PROOF TESTING: Proof testing is completed per customer request and/or at Skookum’s discretion. As a rule, poofing of Skookum shackles requires testing at twice the stated Working Load Limit (WLL), or as required by ASME B30.26, Chapter 26-1, or in accordance with the RRC-271. In some cases, the standard Skookum proof test exceeds both of these specifications and Skookum should be consulted with any special proof test requirements. Standard process on all RR-C-271 proof testing shall be single point loading. All other Proof Tests shall fill up to 80% of the jaw width to properly center the load on the pin. It is recommended that spacers or washers be used to center the load during normal operations so no accidental side loading occurs. See Figure SL-001.1 for recommendations using Skookum Shackles with Slings. See Figure SL-001.2 side loaded reduction table for pad eye configuration. In all cases the pad eye width should be at least 80% of the Jaw width. For special testing purposes such as periodic Magnetic Particle Inspection after proof testing see below for maximum percentage allowances for removing tooling/forging marks/ and minor indications. If grinding exceeds these percentages parts should be removed from service and Skookum Engineering should be consulted.