TM 10-3930-671-24 PM Service Intervals Typical Operating Conditions NOTE Since the operating environment of lift trucks varies widely, the following descriptions are highly generalized and should be applied as actual conditions dictate. Time  intervals  between  PMs  are  largely  determined  by  operating  conditions.  For  example,  operation  in  sandy,  dusty locations requires shorter maintenance intervals than operation in clean warehouses. The indicated intervals are intended for normal operation. To allow better understanding of this aspect, the following clarification should be made: Normal Typically, four to eight hours of operation, mostly in buildings or in clean, open air, smooth floors, and pavement. Severe Prolonged operating hours or constant usage. Rough floors, broken semi-improved pavement. Extreme 1. In sandy or dusty locations, e.g., airborne abrasives or contaminants. 2. High-temperature environments. 3. Environments with extreme temperature changes. 4. Rough floors and pavement. 5. Extensive brake application. If  your  fork  lift  truck  is  used  in  severe  or  extreme  operating  conditions,  you  must  shorten  the  maintenance  intervals accordingly. Recommended PM Intervals The maintenance time intervals  referred  to  in  this  manual  relate  to  truck  operating  hours  as  recorded  on  the  hourmeter and based on experience which Clark has found to be appropriate under typical (normal or average) operating conditions, as follows: A = 8 - 10 hours, or daily B = 50 - 250 hours, or every month (Typical PM interval) C = 450 - 500 hours, or every 3 months D = 900 -1000 hours, or every 6 months E = 2000 hours, or every year F-38