As already described, preloading value v represents an important criterion for the functioning of the MarMotion high-precision rotary stroke bearing. It influences the loading capacity, the smooth running and, if the recommended values are exceeded, the service life.
Avoid pressing the guide bush!
Avoid pressing the guide bushes as this may damage the micro-finished guide diameter d1. The bush adapts to the location bore. This results in form errors and excessive preloading, thereby impairing the correct functioning of the rotary stroke bearing. Clamp-type fittings and pressure screws are also unsuitable for the same reasons.
The tolerance of outside diameter dB of the MarMotion guide bushes corresponds to ISO-n4 (or ISO-h6 for type N 570). The tolerance of the location bore should be selected so that there is no press fit of the guide bush.
Separate ball operating zones
Flange with stop bit
Cap Sealing rings, wiper seals
Installation with seals
A seal is necessary when there is a lot of dirt present, especially when this takes the form of abrasive substances or if particularly high demands are placed on smooth running, ease of movement and durability.
Unlike the guide bush, the guide shaft can be clamped or pressed in.
Clamping in the location bore, e.g. ISO-H6
Clamping in vee-block
Poorly aligned location bores can result in tension in the shaft and rotary stroke bearing. This can be prevented by providing the bores with some fitting clearance, e.g. ISO F7-H7. At the final assembly stage, glue the shafts together with the rotary stroke bearing and allow to harden when properly aligned. The manufacturers' gluing instructions in terms of the gluing aperture, hardening time, etc. must be adhered to.
|If ball cages are used in conjunction with open guide bushes, the ball cage and the guide shaft should run together into the bush. Since undersizing (preloading) is employed, this method is only one that can prevent the balls sliding between the bush and shaft.|
In the case of rotary stroke bearings with closed guide bushes, the guide shaft must be inserted against the preloading pressure. Lubrication grease is advisable to prevent the balls becoming flattened.
Particularly in the case of ball cages with larger diameters, it must be ensured that the cage is properly centered in the guide bush.
Despite the fact that the guide moves non-positively subject to preloading, the ball cage can alter its position axially ("cage creeping").
Safety rings in the bush
|Safety rings on the shaft|
Safety rings on the ball cage
Pressure spring on one side
Pressure springs on both sides
Shafts with the clamping modes illustrated below can be produced on request.
• with inside thread
In addition to the standard series, guide bushes can be custom-made to suit the customer’s specific dimensions and design requirements.
• with recesses for clamping with safety rings
Special dimensions differing from those listed in the tables are available on request – in small-scale production lots – for all ball cage ranges.
Examples of special designs:
• ball cages with balls in special stainless rolling bearing steel (1.4112)
We would be pleased to advise you if you have any questions.