11. May dao mot gau
a. Cong dung va phan loai
* Cong dung: May dao la mot trong nhung loai may chu dao trong cong tac lam dat noi rieng va trong cong tac xay dung noi chung. May dao chuyen lam nhiem vu khai thac dat va do vao phuong tien van chuyen, hoac chung tu dao va van chuyen dat trong pham vi cu ly ngan nhu dao dap kenh muong.
Trong cac cong trinh xay dung duong xa, de dap, thuy dien, khai thac mo v.v... may dao mot gau duoc liet vao may quan trong nhat. Theo thong ke o nhieu cong trinh xay dung, khoi luong dat do may dao dam nhiem chiem tren duoi 50% tong khoi luong.
Ngoai cac cong viec dao dat, xuc dat da, vat lieu xay dung v.v.. may dao con lam duoc nhieu cac cong viec khac nhu: truc cau cac thiet bi va vat lieu nang len cao, lam bua dong coc v.v. Nguoi ta thuong thiet ke them cac bo cong tac de may dao co the hoan thanh nhieu cong viec theo yeu cau cua dieu kien thi cong nhu thiet bi bo cong tac gau thuan, bo cong tac gau nghich, bo cong tac gau quang, bo cong tac gau ngoam, bo cong tac gau bao, bo cong tac can truc, bo cong tac bua dong coc.
* Phan loai: May dao co the duoc phan loai theo cac cach sau:
- Theo dac diem bo cong tac: may dao gau thuan, may dao gau nguoc, may dao gau ngoam, may dao gau keo (gau day quang), may dao gau bao...
- Theo he thong treo bo cong tac: he treo mem (cap) va he treo cung (xi lanh thuy luc).
- Theo he thong di chuyen: di chuyen xich va di chuyen banh hoi.
- Theo co cau dieu khien gom: may dao dieu khien co khi, may dao dieu khien thuy luc, may dao dieu khien hon hop.
- Theo dung tich gau dao nguoi ta chia ra cac loai:
+ May dao loai nho: co dung tich gau tu 0,15 den 1 m3.
+ May dao loai trung: co dung tich gan tu 1,25 den 4 m3.
+ May dao loai lon: co dung tich gau tren 4 m3.
b. So do cau tao va nguyen ly lam viec cua may dao mot gau.
Cau tao tong the cua may dao mot gau gom cac bo phan co ban sau:
- Thiet bi lam viec (gom: gau, tay gau, can).
- Thiet bi dong luc va truyen dong (dat tren san quay).
- Thiet bi di chuyen (banh xich hay banh lop).
+ May dao gau thuan (gau ngua).
May dao gau thuan thuong duoc dung de dao dat, da, quang o muc cao hon mat bang may dung, qua trinh do dat duoc xa qua day gau. Trong xay dung thuong su dung loai may co dung tich gau tu 0,153,2 m3, khi khai thac mo su dung loai may co dung tich gau toi 20 m3.
Bo cong tac cua may dao gom can, tay gau co lap gau voi mep cat lien hay co rang gau. Can co phan duoi noi voi san quay bang khop ban le. Gau thuong co dang hinh khoi chu nhat hoi rong ra o phia duoi, day gau co the dong mo nho co cau dong mo rieng. So do cau tao cua may dao gau thuan dieu khien bang thuy luc duoc cho o hinh 3.1. Hinh 3.1. Cau tao chung may dao thuy luc gau thuan
1- Gau; 2- Tay gau; 3- Xi lanh quay gau; 4- Can; 5- Xi lanh tay gau; 6- Xi lanh can; 7- Ban quay; 8- Xich di chuyen.
Qua trinh lam viec cua may dao gau thuan dien ra nhu sau:
Khi bat dau dao, gau duoc ha xuong, dong thoi dieu khien tay gau va gau dua gau ve vi tri cat dat. Tiep tuc dieu khien de tien hanh vua cat dat vua muc dat day gau. Khi gau day dat dua gau ra khoi tang dao, quay may dua gau ve vi tri do dat. Toi vi tri do vua ha gau vua mo day gau xa dat. Sau khi xa het dat gau duoc quay tro ve tang dao, luc nay do trong luong ban than day gau quay quanh khop, tao ra luc day chot vao lo, gau duoc day lai va tiep tuc chu ki dao dat moi.
