Recommendation should be obtained from Power Jacks on this type of application and a completed application analysis form submitted. In general, semi-continuous operation can be permitted where load is light as compared to screw jack rated capacity. Units so used should be lubricated frequently and protected against dust and dirt. High duty screw jacks such as the S-Series, are oil-lubricated and are designed for maximum duty cycles. Special designs of screw jacks fitted with ball screws or roller screws may also suit high duty applications, consult Power Jacks Ltd for details.