Westfield Fasteners Product Specification:
DIN 603 & DIN 555 - Coach Bolts (Cup Head Square Neck Bolts) with Nuts
This product guide contains the specification for metric threaded coach bolts / carriage bolts when supplied with matching nut as available from Westfield Fasteners. The basis of this specification is the DIN standards DIN 603 and DIN 555.
Generally used in timber to timber and timber to metal construction, these bolts incorporate a square neck to grip the hole in the timber when fitting, and therefore negates the need for any drive recess to be included on top of the head. Supplied to DIN 603 and DIN 555. Usually manufactured with a full thread, though often some stock may include a partially threaded shank, particularly on longer lengths. Comes complete with hexagon nut to fit.
Scope of the ISO standard.
DIN 603 specifies the tolerances and the permissable variation in form of carriage bolts / coach bolts / cup head bolts, and covers metric thread diameters from M5 up to and including M20. Similarly, DIN 555 does so for the nuts. Mechanical properties for these items are defined in ISO 898 and ISO 3506.
Table 1 below defines the overall dimensions and tolerances of this screw type, whilst table 2 defines the tolerances on the shank length. Table 3 defines the detail of the accompanying nut.
Figure 1: Socket Head Countersunk Screw
Notes to figure 1:
- There may be up to 2 incomplete threads at the end of the bolt (a).
Variations from DIN 603 & DIN 555
In our experience, we find that these coach bolts are most often supplied with nuts conforming to DIN 934 instead of DIN 555. Please see the data sheet for DIN 934 for these specifications, which have minor variations in the dimensions compared to DIN 555.
With regard to thread lengths, the manufacturers often stray away from the standard when deciding how much thread to apply to the shank on these bolts. Therefore, the thread lengths quoted in table 2 should be considered a minimum, and should be taken as a guide only.
