KM Thompson
Member
I have a ’73 450B loader and I have the May-87 edition of TM-1033.
My machine has the same fault as described at the bottom of page 70 5-7: when I slowly move the lever back to the raise position, the loader boom settles before it raises (it also settles a bit when I release the lever, both in raise and lower). The manual states that this is probably the result of the ‘check valve’ leaking.
In Fig. 7 on page 70 20-5, two check valves are shown: the ‘Check Poppet’ (4) and the Anti-Cavitation Check’ (18), (which, based on the ‘2500’ stamped into the cover, is actually the boom raise circuit relief). There are also various relief valves (1, 11, 15).
On the original boom valve, the seat for the poppet valve had worn in an oval shape. I took the valve body to my local machine shop and he reground the seat, re-bored the valve guide in the plug (7) and fab’d a new poppet valve with a larger diameter shaft and head.
When I installed this back in the machine, it didn’t offer much, if any, improvement. I then bought a used unit from Wenger’s. Before installation, I checked the poppet valve, the valve seat and the valve guide in the plug and none had appreciable wear. I installed this unit and same results: the loader boom settles before it raises.
My question is: what is the manual referring to when it mentions a ‘check valve’ on page 70 5-7? In the text beneath Fig. 7 on page 70 20-5, there is the ‘Check Poppet’ and the ‘Anti-Cavitation Check’ but no ‘check valve’.
My machine has the same fault as described at the bottom of page 70 5-7: when I slowly move the lever back to the raise position, the loader boom settles before it raises (it also settles a bit when I release the lever, both in raise and lower). The manual states that this is probably the result of the ‘check valve’ leaking.
In Fig. 7 on page 70 20-5, two check valves are shown: the ‘Check Poppet’ (4) and the Anti-Cavitation Check’ (18), (which, based on the ‘2500’ stamped into the cover, is actually the boom raise circuit relief). There are also various relief valves (1, 11, 15).
On the original boom valve, the seat for the poppet valve had worn in an oval shape. I took the valve body to my local machine shop and he reground the seat, re-bored the valve guide in the plug (7) and fab’d a new poppet valve with a larger diameter shaft and head.
When I installed this back in the machine, it didn’t offer much, if any, improvement. I then bought a used unit from Wenger’s. Before installation, I checked the poppet valve, the valve seat and the valve guide in the plug and none had appreciable wear. I installed this unit and same results: the loader boom settles before it raises.
My question is: what is the manual referring to when it mentions a ‘check valve’ on page 70 5-7? In the text beneath Fig. 7 on page 70 20-5, there is the ‘Check Poppet’ and the ‘Anti-Cavitation Check’ but no ‘check valve’.
