18. Phan tich uu, nhuoc diem va pham vi su dung cua cac may dam len tinh? Phuong phap thay doi taI trong dam o cac may dam len tinh.

a. Lu banh cung tron:

Lu banh cung tron la loai may dam don gian nhat (hinh 5-3) co the keo theo hoac tu hanh. Loai lu nay gom banh lu tron bang thep 4, khung 2 va moc keo 1. Banh lu lien ket voi khung bang o truc 3. Qua nap gia tai 6 co the do cat vao trong qua lan de tang ap luc len dat khi can thiet. Tren khung con lap bo phan gat dat dinh 5. Loai nay dung may keo hoac dau keo de keo theo. Lu banh cung tron khong nen dung trong thi cong nen mong cong trinh do chieu sau dam nho 0,150,20m, be mat datdap, sau khi dam de tro thanh nhan min lam cho lop dat dap tiep theo kho dinh ket voi lop duoi, suc bam cua may kem, may cong kenh, nang va cham. May chi phu hop khi dam be mat dat co lan da, trong thi cong duong oto, dam nhung lop dat hoan thien ke ca lop ao duong betong nhua.

lu banh cung tron keo theo:1- Moc keo; 2- Khung; 3- o truc; 4- Banh lu; 5- Bo phan gat dat dinh; 6- Nap gia tai.

b. Lu banh lop

Lu banh lop la loai may dam tinh duoc su dung kha pho bien de dam dat cung nhu dam ket cau be mat cong trinh duong. So voi lu banh cung tron, lu banh lop co cac uu diem sau:

- Chieu sau dam lon hon so voi lu banh cung tron, co the dat tu 4045cm,

- Thich hop voi nhieu loai nen dat khac nhau do thay doi duoc ap luc de len nen bang cach thay doi trong luong va ap suat hoi trong banh (thuong tu 36 at).

- Nang suat may cao, toc do lu len lon (loai keo theo dat tu 35 km/h, loai ban tu hanh dat 1015km/h, loai tu hanh dat 2025 km/h).

Lu banh lop loai nho co trong luong 515 tan, loai vua 1550 tan, loai lon 50100 tan va co the lon toi 200 tan.

Dau keo; 2. Co cau yen ngua; 3. Khung; 4. Xylanh dieu khien; 5. Thung xe; 6. Tam gat lam sach; 7. Lop xe; 10. Tam gia tai; 12; Moc keo.

Lu banh lop co the tu hanh (hinh 5-4b) hoac keo theo (hinh 5-4a) gom mot khung 3 ty len co cau yen ngua 2 cua dau keo 1, hoac noi truc tiep bang moc keo 12 voi may keo hay oto. Cac lop xe 7 duoc lap thanh mot hoac hai hang tren mot truc hoac hai truc. Thung xe 5 chua dat, cat, da hoac mot tam gang 10 (hinh 8.4a.), hay be tong duc san; hoac nhieu tam gang; co the dat vao hay lay ra de dang de dieu chinh luc dam. Xylanh 4 lam nhiem vu dieu khien (lai) xe lu (hinh 5-4b).

Cac may lu chan cuu:1- Xe keo mot truc; 2- Khung keo; 3- Banh lu (trong lan); 4- Vau chan cuu; 5-Cua gia tai.

Co loai lu chan cuu hoat dong hai chieu va hoat dong mot chieu.