Reference 70™ Bolts

REF 70™ Elevator Bolts

Reference 70™ (REF 70™) are ISO grade 5.8 elevator bolts with a concave head and four lugs on the underside to help prevent rotation when tightening. The REF 70™ bolt, when coupled with the special oval washer, is ideal for steel elevator buckets in heavy-duty industrial applications on larger diameter pulleys over 50 cm in diameter. Because of this domed area under the bolt head, these bolts are not recommended for flat back plastic buckets, especially on thinner belts.

Ref70 elevator bolts
Product Features: 
  • Steel / Stainless steel 304 & 316
  • Steel - ISO grade 5.8
  • Concave bolt head with 4 lugs on the underside to prevent rotation when tightening
  • Whitworth or metric
  • Bolt types: M6, M8, M10, M12
Head Diameter
Max. Torque
Package Quantity
Package Weight
M6 x 121/4 x 1/21751001.04
M6 x 20*1/4 x 3/41751001.18
M6 x 25*1/4 x 11751001.24
M6 x 301/4 x 1-1/41751001.48
M6 x 401/4 x 1-1/21751001.56
M8 x 205/16 x 3/423101002.08
M8 x 25*5/16 x 123101002.38
M8 x 30*5/16 x 1-1/423101003.54
M8 x 40*5/16 x 1-1/223101002.90
M8 x 505/16 x 223101003.24
M10 x 253/8 x 127181003.94
M10 x 30*3/8 x 1-1/427181004.44
M10 x 40*3/8 x 1-1/227181004.80
M10 x 45*3/8 x 1-3/427181005.08
M10 x 50*3/8 x 227181005.36
M10 x 553/8 x 2-1/427181005.50
M10 x 653/8 x 2-1/227181005.72
M12 x 301/2 x 1-1/435421007.44
M12 x 401/2 x 1-1/235421007.78
M12 x 451/2 x 1-3/435421008.12
M12 x 501/2 x 235421008.44
M12 x 551/2 x 2-1/435421009.08

* Available in stainless steel

Large Oval Washer

Use with Ref 70 bolts in heavy duty applications.

  • Available in Zinc-Plated Steel / Stainless Steel 304
  • Locates over 4 lugs on bolt head, increasing effective bolt head size and bolt holding
  • Belt must be thick enough to absorb the washer and / or the bucket belt holes should be recessed
  • Not recommended on pulley diameters of less than 20” (500mm)
  • Fit the longest part of the oval across the belt width


Elevator Bolt Hardware - Nuts, Washers & Spacers

Along with the various types and sizes of elevator bolts, 4B offers all of the hardware required for each fastener.         
For more information on all elevator bolt hardware specifications, see page 5 of our full bolt catalogue by clicking the link below.

More info

Is the installation of Ref70 bolts any different to other elevator bolts?

When using the large Reference 70™ (REF 70™) oval washer with the REF 70™ bolt, the washer should be placed with the widest part across the belt in order to minimize stress on the system as it passes around the curved pulley. 

Note:  the bolt head and oval washer are installed on the back of the belt.  
Ref70 installation

FAQ - Elevator Bolts

How long of an elevator bolt do I need?  
  When installing buckets on an elevator belt, use this simple formula:  
  (belt thickness + bucket back thickness + washer thickness + nut thickness + 1/4 inch)  
What grade are 4B elevator bolts?  
  4B elevator bolts meet or exceed ISO Grade 5.8 / SAE Grade 2 standards.  The bolt grade guide below is for bolt diameters of 6mm (1/4") to 12mm (1/2"):  

ISO Grade SAE Grade Min. Tensile Strenghth (psi)
5.8 2 74000
8.8 5 120000
10.9 8 150000

What torque setting should I use?  
  An ideal installation will result in the elevator bolt head fitting snuggly just below the surface of the belt after tightening (Image B).  However, never exceed the maximum recommended torque as shown in the tables below:  

Bolt Dia. in. lbs. ft. lbs. nm
M6 72 6 8
M7 115 10 13
M8 168 14 19
M10 336 28 38
M12 588 49 66


bolt dia. in. lbs. ft. lbs nm
1/4" 72 6 8
5/16" 156 13 18
3/8" 276 23 31
1/2" 684 57 77


How do you install an elevator bolt?  
  The head of the elevator bolt should lie against the inside surface of the elevator belt with the nuts and washers on the inside of the elevator bucket.  An ideal installation will result in the elevator bolt head fitting snuggly just below the surface of the elevator belt.    

  Do you have any maintenance recommendations?  
  After initial installation, it is recommended that the bucket elevator be run for approximately four hours.  After which the bolts should be re-tightened to ensure that there are no loose parts.  Periodic inspections are always recommended to  check for any issues that may occur during the life of the elevator, including checks for loose or damaged elevator bolts.  

Ref70 elevator bolt
Ref70 elevator bolt with small flat washer & hexnut
Ref70 elevator bolt with domed washer

Bucket Elevator Design Service

Bucket Elevator Design Service

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Take advantage of 4B's free, guaranteed worldwide technical support service from a team of engineers specialising in the design and calculation of bucket elevators.. Using your key technical data, our engineers can give you a detailed technical recommendation for the ideal bucket elevator with the ideal capacity and discharge characteristics. We can either design your new bucket elevator or we can help you to increase the capacity of your existing bucket elevator.

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Elevator Bolts Catalogue

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