H4-VV27-B nt equalizes the shaft offset and absorbs impacts Helical gear boxes H4

Flender/Flender Gear Units/Helical gear boxes H4

gh cooling capacity, with no defrosting problems; are less costly; and are lighter in weight than mechanical refrigerationsystems (Ryall and Pentzer, . Nevertheless, the advantages of these systems are offsetby some severe problems in their use. Excessive concentrations of 2or CO 2gases create risks of freezing and/or suffocating the workers (ASHRAE, . High concentrations of such gases may also be harmful to certain types of horticultural produce. It is knownthat an atmosphere lled with 1% 2causes physiological disorders on most fruits and vegetables, even though many of them can withstand high levels of 2for several days with no injury (Ashby, . In spite of the fact that moderate levels of CO 2can retard 5 Hui et al. produce decay and ripening, high concentrations may cause off-avors, off-colors, and physiological disorders (Ashby, . Leafy green vegetables are found to be incompati-ble with CO 2refrigeration systems (McGregor, . Furthermore, liquid CO 2must be stored at pressures higher than 4 kPa (gauge) and below 3 (ASHARE, . The possibility of very low cargo temperatures as result of an excessive accumulation of gases and the problem of availability of recharging gases in transport points make liq- uid cryogenic cooling less acceptable for use in fruit and vegetable transport (Ryall andPentzer, . 3.2.3.2 Dry Ice Solid CO 2or dry ice may be used in the form of blocks, snow, or pellets in transport vehicles. It is mostly used in frozen food and ice cream delivery trucks (Ashby, but is also used during the air transport of strawberries (ASHRAE, . Direct contactwith dry ice should be avoided to prevent damage to the produce (McGregor, . Dryice is sometimes used in air cargo along with iced water, to slow the melting of iced waterand prolong the cooling period during transport (ASHRAE, . 3.2.4 Heating During Winter During winter, when outside temperatures are lower than the temperature required inside the vehicle, the transport vehicles mu