5. Cong dung, phan loai, cau tao va nguyen li lam viec cua may truc dang cau.
1. Khai niem va phan loai
a. Khai niem: Cau truc duoc dung chu yeu trong cac phan xuong, nha kho de nang, ha va van chuyen hang hoa voi luu luong lon. Cau truc thuong co ket cau dam hop hoac dan, tren do dat xe con co co cau nang ha vat. Dam cau co the chay tren cac duong ray dat tren cao doc theo nha xuong, con xe con co the chay doc theo dam cau. Vi vay ma cau truc co the nang ha va van chuyen hang theo yeu cau tai bat ky diem nao trong khong gian cua nha xuong.
b. Phan loai: Cau truc va cong truc (cong truc khac cau truc la dam cau dat tren cac chan cong voi cac banh xe di chuyen tren ray dat o duoi dat).
+ Cau truc
* Theo cong dung: Cau truc cong dung, cau truc chuyen dung.
* Theo ket cau dam cau: Cau truc loai mot dam, cau truc hai dam.
* Theo cach tua cua dam cau len duong ray di chuyen: cau truc tua va cau truc treo.. Loai cau truc tua duoc su dung pho bien hon.
* Theo cach bo tri co cau di chuyen cau truc: dan dong chung va dan dong rieng.
Ngoai ra theo nguon dan dong co cac loai cau truc dan dong tay va cau truc dan dong bang may. Theo vi tri dieu khien co cac loai cau truc dieu khien tu ca bin gan tren dam cau va cau truc dieu khien tu duoi nen bang hop nut bam. Dieu khien tu duoi nen bang hop nut bam thuong dung cho loai cau truc mot dam co tai trong nang nho.
+ Cong truc
* Theo cong dung
- Cong truc co cong dung chung co tai trong nang 3,210t, khau do dam cau 1040m, chieu cao nang 716m. Cong truc dung de lap rap trong xay dung co tai trong nang 50100t, khau do dam den 80m va chieu cao nang den 30m. Cong truc de lap rap co toc do nang, di chuyen xe con va di chuyen cong truc nho hon so voi cong truc cong dung chung. ( Dac biet co toc do cham dung khi lap ghep, cu the van toc nang ha vat tu 0,05 den 0,1 m/ph va van toc di chuyen xe con cong truc khoang 0,1m/ph. Cong truc co cong dung chung dung de boc do, van chuyen hang the khoi, vat lieu roi trong cac kho bai ben cang hoac nha ga duong sat. Cong truc dung de lap rap duoc dung trong lap rap thiet bi trong nhieu linh vuc, dac biet trong cac cong trinh nang luong va lap ghep cac cong trinh giao thong nhu cau cong. Thiet bi mang vat cua cong truc thuong la moc treo, gau ngoam hoac nam cham dien.
- Cong truc chuyen dung thuong duoc su dung de phuc vu nha may thuy dien.
* Theo ket cau thep: khong co congxon, cong truc co mot dau congxon, cong truc co hai dau congxon. Ket cau dam cau va chan cong cung rat da dang. Dam cau co the duoc che tao duoi dang dam hop han, dam ong, dam dan khong gian va co the la mot dam hoac hai dam.
2. Cau tao chung cua mot so may truc dang cau
a. Cau truc loai mot dam.
Tren hinh 1.19 la hinh chung cua cau truc loai mot dam. Ket cau thep cua cau truc loai nay gom dam cau 1 co hai dau tua len cac dam cuoi 5 voi cac banh xe di chuyen doc theo ray dat tren vai cot cua nha xuong. Co cau di chuyen cau truc mot dam thuong dung phuong an dan dong chung. Phia tren dam chu I la dan thep 4 dat trong mat phang ngang de dam bao do cung can thiet theo phuong ngang cua dam cau. Palang dien 3 co the chay doc theo cac canh thep phia duoi cua dam chu I nho co cau di chuyen palang. Cabin dieu khien 2 duoc treo vao nho ket cau chiu luc cua cau truc. May truc dang nay co the khong co ca bin dieu khien ma dieu khien tu nen thong qua hop dieu khien kieu nut bam.
Hinh.1.19. Cau tao chung cua cau truc loai mot dam
1-Dam cau dang thep chu I; 2-Cabin dieu khien; 3-Palang dien; 4-Dan thep tang cung;5-Dam bien (dam cuoi
b. Cau truc loai hai dam.
Hinh. 1.20. Cau tao chung cua cau truc loai hai dam
1- Cabin dieu khien; 2- Ray di chuyen; 3- Banh xe di chuyen; 4- Dam cuoi; 5- Cap dien; 6- Co cau nang phu; 7- Co cau nang chinh; 8- Xe con; 9- Day treo cap dien; 10- San phuc vu bao duong, sua chua; 11- Dam chinh; 12- Co cau di chuyen xe con; 13- Co cau di chuyen cau truc.
Hai dau cua cac dam chinh 11 duoc lien ket cung voi cac dam cuoi 4 tao thanh mot khung cung trong mat phang ngang, dam bao do cung can thiet cua ket cau thep theo phuong dung va phuong ngang. Tren dam cuoi co lap cac banh xe di chuyen 3 chay tren ray 2 dat doc theo nha xuong tren cac vai cot. Khoang cach theo phuong ngang giua tam cac ray 2 duoc goi la khau do cua cau truc. Chay doc theo cac duong ray tren dam chinh la xe con 8. Tren xe con dat co cau nang 7, co cau di chuyen xe con12. Tuy theo ung dung cua cau truc ma tren xe con co mot hoac hai co cau nang. Truong hop co hai co cau nang thi co cau 7 duoc goi la co cau nang chinh con co cau nang phu 6 co tai trong nang nho hon. Co cau di chuyen cau truc 13 duoc dat tren ket cau dam cau. Cabin dieu khien1 duoc treo phia duoi dam cau. Nguon dien cung cap cho dong co cua co cau nang duoc lay tu duong dien chay doc theo nha xuong va san dung 10 dung de phuc vu cho viec kiem tra, bao tri duong dien nay. Cap dien 5 duoc treo tren day 9 de cap dien cho cac dong co dat tren xe. Ngoai ra tren phan ket cau thep cua cau truc con co phan san dung voi lan can de co the di lai khi kiem tra, bao tri, sua chua. Dam chinh cua cau truc hai dam duoc che tao duoi dang hop hoac dan khong gian. Dam dan khong gian tuy co nhe hon dam hop song kho che tao va thuong chi dung cho cau truc co tai trong nang va khau do lon. Dam cuoi cua cau truc hai dam thuong duoc lam duoi dang hop va lien ket cac dam chinh bang bulong hoac han.
De dan dong cho xe con va cau truc phai su dung co cau dan dong.
c. Cong truc. Cong truc duoc the hien tren hinh 1.22 gom dam cau 2 duoc lap tren chan cung 1 va chan mem 3. Xe con 4 cua cong truc (co the dung palang dien) duoc dan dong theo kieu cap keo va di chuyen tren ray dat phia tren cua dam chinh. Co cau nang va co cau di chuyen xe con duoc dat tren ket cau thep cua cong truc.
Hinh 1.22. Hinh chung cua cong truc
a. Loai khong co congxon; b. Loai co hai dau congxon;
1- Chan cung; 2- Dam cau; 3- Chan mem; 4- Xe con: loai tua (a), loai treo (b).