Single-car shunting

From time to time there have been discussions in various forums about single-car movements failing to reliably shunt track circuits in ABS territory. In the 1940's and later the NYS&W operated the ACF Railiners and assorted doodlebugs (the Erie also operated gas-electrics in ABS territory at that time), and I don't remember hearing of any shunting problems with them or the RDCs that succeeded them in the 1950's. Does anyone know whether the NYS&W "streamliners" had any special equipment to ensure shunting? They put in a lot of miles between Paterson Broadway and Granton Jct., and on the Erie east of there.

When I worked on the M-1 in the late 1980's we found a metal block with a tension rod that rubbed on the wheel treads. My understanding was this was to help improve conductivity to trip the signals.

RDC had severe problems with crossings and signals , each wheel had a scraper block with a bond wire to frame and yes still a single car was not allowed to approach a crossing in excess of 30 mph prepared to stop.
The disk brakes of course did not help as they did nothing to keep wheel tread clean.

single SPV had same restriction despite being almost 30% heavier and having tread brakes.

I think the PRR insisted on clasp brakes on the early Silverliners for just that reason. I'm sure the Railiners and gas-electrics of the 1940's must have had clasp brakes, so maybe that was enough. The Railiners certainly never slowed for crossings. Thanks for answering.

The museum railroad for which I volunteered for many years operated 37+ miles of former Nickel Plate branch. Our timetable included an instruction called the "12-axle limitation." If any consist had 12 or fewer axles, it was required to approach road crossings at restricted speed or slower, prepared to stop for non-working crossing protection. The line was dark, and had a number of road crossings that were used infrequently. Applying sand helped break off the rust and make crossing signals respond more reliably.