Trimming Operation in Vessel
Unloading clamshell buckets and pneumatic unloader have been conventionally used to unload bulk cargoes (grain, salt, sugar, coal, ore fertilizer, chips, etc.) from vessels. However, the bucket scooping amount of unloading materials or suction decreases when the unloading work progresses, resulting in a corresponding deterioration of unloading efficiency.
This reduced efficiency means that vessels must remain longer in port, leading to a direct lowering of vessel operating efficiency and a substantial increase in port charges. Consequently, it has become necessary to find an effective method to facilitate bulk unloading. The conventional method is bulk cargoes were raked manually has been replaced by the bulldozer, and a trimming dozer has now been developed specifically for the handling of bulk cargoes in vessels.
Wheel loaders have often been employed at the final stages of unloading to protect the bottom of the vessel hold, however these have been replaced quite recently by trimming dozers equipped with rubber crawler.
Design Features
(1) Trimming blade
Since the maximum lift (a), maximum drop (b), forward pitch angle (c) and backward pitch angle (d) of the blade are larger than usual and the breast dimension (e) is longer, substantially greater amounts of the bulk cargo can be raked and pushed at a time.
(2) Rear protector
Even if the trimming dozer inadvertently touches the hold frame, shoring, etc., the protector effectively prevents damage to the fuel and hydraulic oil tanks.
(3) Short exhaust pipe
A short exhaust pipe has been fitted to the trimming dozer to reduce overall height.
(4) Slinging hooks
The trimming dozer is provided with slinging hooks to enable it to be lowered into the hold.
(5) Track coming off prevention
Bulk cargo material caught between the tracks and sprocket is released through holes provided in the shoes, and this prevents the tracks from coming off.
(6) Dust preventive measures
Exhaust gas remains inside the hold, and dust resulting from the operation of the blade and the tracks accumulates both inside and outside the trimming dozer. To counter this problem, various measures have been taken.
1) Washable air cleaner inner element
Since the interior of the hold is extremely dusty, the air cleaner element becomes quickly clogged. However, as the inner elements are made of no-woven cloth or urethane and can therefore be washed, maintenance cost is greatly reduced.
2) Facilitation of washing
The trimming dozer requires washing on completion of one operation in readiness for the next to prevent deposits from the first operation being mixed in with the subsequent one. Hinges have therefore been adopted for the radiator grille and undercover to facilitate washing.
(7) Corrosion preventive measures
Bulk cargoes such as salt and potassium chloride corrode the terminals of electrical equipment, leading to short-circuiting. Thus, corrosion-proof alternators and starting motors have been adopted for the trimming dozers, and terminals are coated with silicone compound.
(8) Safety measures
Trimming dozers are equipped with backup buzzers and red color lights to provide ample warning when moving in reverse.
Standard Equipment
Track Shoe Selection
Specifications
* : Including dozer equipment in addition to bare tractor
** : Including cab and air conditioner
*** : To top of cab