(a) 
         The dynamometer shall have a single roll with a diameter of at least 0.400 metre.
     
    
        
        (b) 
         The dynamometer shall be equipped with a roll revolution counter for measuring actual distance traveled.
     
    
        
        (c) 
         Flywheels or other means shall be used to stimulate the inertia specified in  § 86.529.
     
    
        
        (d) 
         A variable speed cooling blower shall direct air to the vehicle. The blower outlet shall be at least 0.40 m  2 (4.31 ft  2) and shall be squarely positioned between 0.3 m (0.98 ft) and 0.45 m (1.48 ft) in front of the vehicle's front wheel. The velocity of the air at the blower outlet shall be within the following limits (as a function of roll speed):
     
    
        
            
                
                
            
            
                | 0 km/h to 5 km/h | 
                0 km/h to 10 km/h. | 
            
            
                | 5 km/h to 10 km/h | 
                0 km/h to roll speed   5 km/h. | 
            
            
                | 10 km/h to 50 km/h | 
                Roll speed ±5 km/h. | 
            
            
                | 50 km/h to 70 km/h | 
                Roll speed ±10 pct. | 
            
            
                | Above 70 km/h | 
                At least 63 km/h. | 
            
        
     
    
        
        (e) 
         The dynamometer shall comply with the tolerances in  § 86.529.
     
    
        
            Code of Federal Regulations
        
        [42 FR 1137, Jan. 5, 1977, as amended at 42 FR 56738, Oct. 28, 1977]